Weather Extremes

Tropical Storm Superlatives for The Pacific Ocean

By: weatherhistorian, 4:45 AM GMT on September 29, 2011

Tropical Storm Superlatives for The Pacific Ocean.

Last week I blogged on tropical storm superlatives for the Atlantic Basin. This week I follow up with the superlatives for hurricanes/typhoons in the Pacific Ocean. Being by far the largest body of water on earth, the Pacific holds most of these superlatives so far as tropical storms are concerned. A full 70% of all tropical storms form here, whether in the Eastern Pacific (normally off the western coast of Mexico) or in the Western Pacific and Southern Pacific Oceans. The only other active region in the world for tropical formation is the Indian Ocean and the Austral-Asian region in the southern hemisphere. Below are the records set in the Pacific, most of which, also happen to be world records.

The table above clarifies the various names and classifications used to identify tropical storms from all regions worldwide Source: World Meteorological Organization. Table from ‘Extreme Weather: A Guide and Record Book.’

This computer mosaic depicts the paths of all tropical storms that formed in the world between 1985 and 2005. As can be seen the majority occur in the Pacific Basin.

Eastern Pacific Hurricane Superlatives

Most Intense Eastern Pacific Hurricane

Hurricane Linda was the most intense tropical storm ever observed in the Eastern Pacific region. The storm formed on Sept. 9, 1997 and reached its peak intensity on Sept. 12th when its central pressure fell to 902mb (26.58”). Its maximum sustained winds were estimated to have reached 185mph at this time. The storm never made landfall aside from passing over the uninhabited island of Socorro Island, several hundred miles south of Mexico’s Baja Peninsula.

A Satellite image of Hurricane Linda when she was at her peak on Sept. 12, 1997 with sustained winds estimated at 185mph. Image from NOAA.

Here is a list of the ten most intense Eastern Pacific hurricanes on record as determined by their lowest observed central pressures:

Deadliest Eastern Pacific Hurricane

The unnamed 15th tropical storm of the season of 1959 came ashore on Mexico’s central Pacific coastline near Manzanillo as a category 4 hurricane on Oct. 27th. Wind gusts of 155mph were measured at this location. An estimated 1,500-2,000 deaths were attributed to the storm in Colima and Jalisco States with 40% of all the structures in Manzanillo destroyed.

Below is a list of the ten deadliest hurricanes yet recorded in the Eastern Pacific region:

Costliest Eastern Pacific Hurricanes

Hurricane Pauline caused $10.3 billion in damages (inflation adjusted 2011 dollars) to the southern Mexican states of Oaxaca and Guerrero when the storm came ashore here on Oct 9, 1997. As many as 400 were killed in the region.

The second costliest Eastern Pacific hurricane, and the strongest ever to strike Hawaii was Hurricane Iniki that slammed into the island of Kauai on Sept. 11, 1992 with 145mph measured wind gusts. $3.2 billion in damage (2011 inflation adjusted dollars) was caused to Hawaii by Iniki and 6 deaths were reported. Iniki also holds the Eastern Pacific record for lowest landfall pressure measured with a 945mb (27.91”) reading when the storm came ashore.

Earliest and Latest Tropical Storms to form in the Eastern Pacific

The earliest tropical storm to form in the Eastern Pacific was TS Alma on May 14, 1990. This was tied by TS One-E again on May 14th in 1996. The latest storm on record was TS Winnie, which survived as such until December 7, 1983.

Heaviest Rainfall Totals Caused by Eastern Pacific Tropical Storms

Hurricane Juliette dumped 39.80” at Cuadano, Santiago in Mexico’s Baja from Oct. 1-3, 2001. Hurricane Hiki in 1950 is reputed to have dropped 52.00” of rain at Kanalohuluhulu Ranger Station, Kauai between Aug. 14-18. More than this may have actually fallen since the 24”-capacity rain gauge was found overflowing when checked on both Aug. 15th and 16th. This is the greatest amount of rainfall ever attributed to a tropical storm in the United States.

Highest Wind Speed Measured during an Eastern Pacific Hurricane

Hurricane Iniki is reputed to have produced the highest measured wind speeds during any Eastern Tropical storm on record when it struck Kauai, Hawaii on Sept. 11, 1992.

According to the Honolulu Advertiser, “The National Weather Service reported wind gusts of up to 175 mph (280 km/h). The highest recorded wind speed from Hurricane Iniki was a 227 mph (365 km/h) reading from the Navy's Makaha Ridge radar station. That remarkable figure was recorded at a digital weather station whose wind gauging equipment blew off after taking the measurement during the storm.”

I have not been able to confirm this remarkable claim. Dr. George Pararas-Carayannis writes the following on his web site featuring Hurricane Iniki, “The maximum of 227mph reported from the Navy Radar Site at Makaha Ridge has been depicted as an anomaly due to improper instrument calibration; therefore unrealistic. I do not entirely agree with that. It may be possible to achieve such wind speeds from funneling (venturi) effects.”

Hurricane Iniki as she ripped through Lihue, Kauai on Sept. 11, 1992. Photo by Bruce Asato, courtesy of the Honolulu Advertiser.

Western Pacific Typhoon Superlatives

Most Intense Typhoon

This, of course, was the famous Typhoon Tip, largest and most powerful tropical storm yet recorded anywhere on earth.

Super Typhoon Tip formed in the western Pacific on October 5, 1979. Slow to develop and exceedingly erratic in its early movement, Tip eventually grew into a monster with a circulation and cloud formation 1,350 miles in diameter.

If such a storm were centered in the Gulf of Mexico, it would extend from Miami, Florida, to Amarillo, Texas. Tip’s gale-force winds extended out from its eye in a radius of 683 miles, about five times greater than a typical Atlantic hurricane. At its peak on October 12, the air pressure in the eye fell to 870mb (25.69”) the lowest ever measured at sea level on the planet, and the equivalent of what normal air pressure would be at an altitude of about 2,500 feet. Winds circulating around Tip’s eye were blowing at a sustained rate of 190 mph with gusts probably well over 200 mph. The eye wall extended up to 55,000 feet, where infrared temperatures were measured at an incredible –135°F. Fortunately, Tip never made landfall, although it took a shot at Guam, swerving at the last moment to the west and thus sparing the small and vulnerable island.

By October 18, Tip had accelerated towards the northwest and was rapidly losing power. By the time it brushed Japan on October 19 and 20, it was much tamer with the wind blowing in gusts at only 88 mph along the runways at Tokyo’s airport.

Super Typhoon Tip is reported having been the largest tropical storm ever observed anywhere in the world. Above is a graphic illustrating the storms size in comparison to the contiguous United States.

It is worthy to note that there have been at least 15 Pacific typhoons of greater intensity than Hurricane Wilma, the strongest hurricane of record in the Atlantic Basin.

Below is a list of the top ten most intense typhoons on record in the Pacific Basin north of the equator (note that there are no comprehensive records for Pacific Typhoons prior to 1959):

Fastest Intensification

Super Typhoon Forest formed in the Western Pacific in September 1983. At one point its central pressure fell an amazing 102mb in 24 hours, from 978mb (28.87”) to 876mb (25.86”). The storms winds increased from 75mph to 175mph during this same time period. This is the fastest 24-hour intensification of any tropical storm yet observed in the world.

Highest Measured Wind Speed in a Pacific Typhoon

A wind gust of 191mph was measured at a weather station on the island of Miyakojima in Japan’s Ryukyu Islands on Sept. 5, 1966 during the passage of super typhoon Cora. Higher wind speeds, of course, have been estimated in many other typhoons. A wind gust of 236mph was reported at Anderson AFB on Guam during the passage Typhoon Paka on Dec. 16, 1997. An investigation, however, discovered the instrument making the measurement was not reliable.

Deadliest Typhoon

The deadliest typhoon in modern history was that which struck Haiphong, Vietnam on Oct. 8, 1881. The storm surge flooded the city and surrounding low level areas resulting in the deaths of an estimated 300,000 people.

More recently, Typhoon Nina in August 1975 is estimated to have been responsible for 86,000 (official estimate) to 230,000 (unofficial) deaths in China as a result of flooding caused by the collapse of the Banqiao Dam in Henan Province. This disaster was kept as a state secret until the Chinese government in 2005 released details concerning such. It was kept secret because of the construction of the Three Gorges Dam on the Yangtze River that was promoted as a panacea for China’s flood wows. Most documents pertaining to the 1975 catastrophe are still secret and the Chinese government has successfully blocked web sites relating to the death toll even as I write this today (aside from their own sanctioned versions).

The reason is that the rainfall from Nina exceeded by a large margin that any dam in China is expected in a 2000-year return period. Those of you familiar with my book Extreme Weather: A Guide and Record Book will remember that I had mentioned (on page 121) all-time world record point rainfalls attributed to “Muduocaidang, Inner Mongolia, China ”of 33.07” in 6 hours, 41.34” in 8 hours, and 55.12” in 10 hours in August 1977”.

I made a trip to China several years ago in order to verify these fantastic world-record point rainfall records. I could find no reference to a site named ‘Muduocaidang’ in China or a reference to the extraordinary rainfalls of 1977 attributed to such. Now, with new evidence available, I realize that these precipitation figures were for August 1975 not August 1977, and were, in fact for a site near the Banqiao Dam in Henan Province.

The fact that such rainfall rates are unprecedented and, should such ever occur again, they would compromise the largest dam in the world (Three Gorges). That is why these records, and one of the greatest and deadliest natural catastrophes on record, have been kept secret until recently. Needless to say, should such an event recur in the Three Gorges Dam region, and the dam compromised by such, perhaps millions of lives would be lost. However, we can take some comfort in that the dam building technology of China is vastly superior to what it was in the 1970s.

It is possible that even deadlier storms have occurred in pre-modern times. A typhoon in July 1780 is reported to have killed 100,000 in Eastern Asia. The famous Hakata Bay Typhoon in 1281 destroyed Kublai Khan’s 2,200-ship invasion fleet headed for Japan drowning 45,000-65,000 of his army. This event caused the word kamikaze to enter the Japanese lexicon, its meaning being ‘divine wind’. Japan’s deadliest typhoon was that which struck Nagasaki on Sept. 17, 1828. The storm surge drowned at least 15,000.

Greatest Rainfall Reported in a Pacific Typhoon

A typhoon affecting Taiwan deposited 108.31” of rainfall in three days Oct. 17-19, 1967 at Xinliao. Of this, 65.88” reportedly fell in one calendar day on Oct. 17th. This figure has been considered controversial however. More recently 91.60” fell at Weilaoshan, Taiwan during 3 days Aug. 6-8, 2009. Of this 55.20” fell on the single day of Oct. 8th.

Most and Fewest Typhoons Reported During any Single Season

The busiest season for Western Pacific tropical storms was 1964 when a total of 39 storms were reported (plus an additional 5 tropical depressions). Of these 13 were tropical storms, 19 typhoons, and 7 super typhoons. The year with the most super typhoons was 1965 when 11 such were reported.

The quietest season was that of 2010 when only 14 tropical storms were recorded (and 5 tropical depressions).

Greatest Storm Surge in the Pacific Ocean as a result of a Typhoon

A storm surge of some 46 feet was reported to have swept over the Marshall Islands during a typhoon on June 30, 1905. This is considered most likely inaccurate since such a surge would have submerged the entire island affected, so how the height was determined remains a mystery. A storm surge of 40 feet inundated Tahiti on Jan. 13, 1903 drowning at least 1000 people.

A typhoon blasts Polynesia’s Arutua Atoll in 1983. Photo by Philippe Mazellier.

Next week I will wrap up this series on tropical storm superlatives with the details for tropical storms of the Indian Ocean and Australian region.

Christopher C. Burt
Weather Historian


Atlantic Basin Tropical Storm Superlatives

By: weatherhistorian, 9:23 PM GMT on September 23, 2011

Atlantic Basin Tropical Storm Superlatives

The normal peak of tropical storm activity for both the Atlantic and Pacific Basins has just been reached this past week or so. Of course, many years bring their most powerful hurricanes or typhoons well after this ‘peak’ period and, in fact, some of the records for storm strength have occurred well into October. Below is a summary of some tropical storm ‘superlatives’ from the Atlantic Basin region. This includes the Caribbean and Gulf of Mexico where the most intense hurricanes on record have formed. Next week I will cover the Pacific and Indian Ocean areas.

This chart illustrates the worldwide frequency of tropical storms (blue area) and storms of hurricane/typhoon intensity (pink area) by month of occurrence. Graphic from “Extreme Weather: A Guide and Record Book” derived from data compiled by Charles Neumann.


HURRICANE WILMA: Hurricane Wilma holds several of the ‘greatest hurricane on record’ superlatives. Using the criteria of lowest barometric pressure measured, Hurricane Wilma became the most intense hurricane ever recorded in the Atlantic Basin on October 19, 2005. Its central pressure fell to 882mb (26.05”) early that day while approaching the Yucatan Peninsula of Mexico. Wilma also holds the record for the fastest intensification of any hurricane when its pressure fell 100mb (2.94”) in 24 hours on Oct. 18-19. In one two-hour period Wilma’s central pressure fell an amazing 45mb (1.32”) between 8pm-10pm on Oct. 18 local time. Wilma also holds the record for the smallest eye observed when it contracted to just 2 miles in diameter when she was at her strongest on Oct. 19th. Hurricane Hunter aircraft had difficulty maneuvering inside the eye at this point.

Two images from space of Hurricane Wilma at her peak when the eye had shrunk to just two miles in diameter. The bottom image was taken by the crew aboard NASA’s international space station at an altitude 222 miles above the storm when it was located 340 miles southeast of Cozumel, Mexico.

Another superlative attributed to Wilma (for the Atlantic Basin at least) was the rainfall she brought to Isla Mujeres at the northern tip of the Yucatan Peninsula when 64.33” of rain fell in 24 hours Oct. 21-22 (with 68” over 48 hours). This is the greatest 24-hour rainfall ever measured not only in the Atlantic Basin from a tropical storm but also anywhere in the world outside of Reunion Island and Taiwan. Wilma’s maximum winds were estimated to have reached 185mph with 220mph gusts at her peak intensity but fortunately these winds and her strength had greatly subsided by the time she made landfall in the Yucatan.


The highest officially accepted wind gust ever measured during the passage of a tropical storm in the Atlantic Basin was 213mph at Pinar Del Rio, Cuba during the passage of Hurricane Gustav on Aug. 30, 2008. Wind gusts of 200mph or more were estimated to have occurred in the Florida Keys during the Labor Day Hurricane of 1935 and possibly when Hurricane Camille struck Pass Christian, Mississippi in 1969.

Below is a list of the highest measured hurricane wind speeds at land sites in North America. These are by no means the highest wind speeds historically attained in hurricanes, just the top ten that were actually measured rather than estimated. Very few anemometers are capable of surviving 150mph+ wind speeds, let alone registering such:

NOTE: The year for the Gustav wind record should read 2008, not 2009. Thanks to WU observer "petewxwatcher" for this correction!


The Great Hurricane of 1780 is reputed to have killed approximately 22,000 people on the islands and in the waters surrounding the Caribbean Islands of Barbados, St. Vincent, St. Lucia, Martinique, Guadalupe, and Dominica between October 10th and 17th of that year. Most of the casualties were sailors in the British fleet that was harbored in the region at that time. The deadliest hurricane in modern times was Hurricane Mitch, which killed an estimated at 19,000 in Honduras and Nicaragua in October of 1998. Below is a chart of the deadliest Atlantic hurricanes in recorded history:

Source from Wikipedia


This is most likely Hurricane Katrina with total damages estimated to be in excess of US$100 billion in 2005 dollars. A possible contender would be the great hurricane of September 1926 that caused close to $100 billion inflation-adjusted dollars worth of damage to Florida and Alabama.


Hurricane Katrina’s storm surge was reported to reach 28 feet along portions of the Mississippi’s coastline in the Gulfport-Biloxi area on Aug. 29, 2005 surpassing the previous record surge of 24.5 feet during Hurricane Camille at Pass Christian, also in Mississippi.


As mentioned above, Wilma holds the record for the lowest barometric pressure ever observed in the Western Hemisphere. Below is a table of the top ten most intense Atlantic hurricanes so far as minimum eye-pressure is concerned:

Source from Wikipedia.


As Jeff Masters mentioned in his blog earlier this week, 2005 produced 28 tropical storms, the most in one season since records have been reliably kept.


Apparently, only one tropical storm formed during the seasons of 1890 and 1914. However, it is likely that some storms went undetected in areas beyond the normal shipping lanes during those years.


This record is held by a single storm: Hurricane Alice which persisted from December 31, 1954 to January 5, 1955, thus becoming both the latest and earliest tropical storm to have formed in the Atlantic Basin.


The San Ciriaco hurricane, named after the town it devastated in Puerto Rico, was in existence for 33 days from its first formation as a tropical depression on August 3, 1899 until it became extra-tropical on September 4th. Of these 33 days it was a tropical storm for 28 days tying Hurricane Ginger of 1971 for top honors.


Twice in recent history there have been four active hurricanes churning in the Atlantic Basin simultaneously. The first time was in August 1893 and the 2nd time in September 1998. One of the 1893 storms eventually came ashore in Georgia and South Carolina killing as many as 2,000 residents of low-lying islands along the coastline.


Tropical Storm Hattie formed off the coast of Nicaragua on October 28, 1961 and then drifted north and west crossing the Central American isthmus before emerging in the Eastern Pacific where it was re-christened Tropical Storm Simone. Two days later, the storm curled back towards the coastline and once again crossed Mexico and emerged into the Gulf of Mexico where it was renamed Tropical Storm Inga.


Hurricane Ivan spawned 119 tornadoes in the eastern U.S. between Sept. 15-18, 2004. Eighteen of the tornadoes reached F-2 intensity (mostly in Florida) and there was even one F-3 in the Remington, Virginia area, unusually strong for such during a tropical storm. Nine deaths were directly attributed to the tornado events.

Hurricane Beulah spawned 115 tornadoes when the storm came ashore near Brownsville, Texas on Sept. 20, 1967. Other reports counted as many as 155 but the 115 figure has been determined as the most accurate according to tornado expert Thomas P. Grazulis. All of the tornadoes occurred in the northern quadrants of the hurricane. There were five reported deaths attributed to the tornadoes.


As mentioned above, Hurricane Wilma produced the greatest 24-hour rainfall ever measured during a tropical storm in the Western Hemisphere. However, greater amounts have been recorded over longer periods of time. The most on record for a single tropical storm is the 112.80” that fell at the Silver Hill Plantation, Jamaica over the course of 5 days Nov. 5-9, 1909. Hurricane Daisy in 1962 did not directly strike Cuba, but moisture inflow from the Caribbean caused by the storm resulted in 79.72” of rain falling over a 3-day period at Tacajo, Cuba between Oct. 4-6.

Next week I’ll blog on typhoon and cyclone superlatives of the Pacific and Indian Oceans.

Christopher C. Burt
Weather Historian


August 2011 Global Weather Extremes Summary

By: weatherhistorian, 3:40 AM GMT on September 11, 2011

August 2011 Global Weather Extremes Summary

August was yet another busy month for global weather extremes. Highlights included record-busting heat and drought (again) in the south-central portions of the U.S.A. The climatological summer of June-August was the 2nd warmest since accurate measurements began in 1895. An intense heat wave also affected southern Europe in mid-month. Severe tropical storms lashed the eastern seaboard of the USA (Irene) and the Philippines and Japan. Torrential rains caused devastating flooding and landslides in Nigeria and Uganda. But the 2nd most important extreme weather story (2nd to the USA heat wave and drought) was the record cold wave and blizzard that hit New Zealand on August 14-15.

Below are the month’s highlights.


August was the 2nd hottest such on record for the contiguous U.S.A. with the average of 75.7° falling just short of the 75.8° recorded in August 1983. For Texas and Oklahoma it was the warmest month (any month) on record. In fact, the average temperature for Texas for the month of August was 88.1°, the warmest recorded for any state during any month. Several cities broke their all-time maximum temperature on record. For all the details of the temperature records broken see my previous blog.

This map plots the number of 100°+ days recorded during the summer of 2011 across the nation.

The drought in Texas intensified (culminating in devastating wild fires in September). Midland, Texas, for instance, has reported only .63” of precipitation since October 1, 2010 (normal amount for this period is 12.79”). The .63” is about half of what Death Valley (normally the driest location in the United States) has recorded.

Meanwhile, in contrast, portions of the mid-Atlantic recorded their wettest single month on record thanks to the intense rainfall generated by Hurricane Irene. The following cities are some of those that reported their wettest month (any month) on record: New York City 18.95” (old record 16.85” in Sept. 1882), Philadelphia 19.31” (old record 15.82” in Aug. 1867), Trenton, NJ 16.10” (old record 15.22” in July 1880), Allentown, PA 13.47” (old record 13.16” in Oct. 2005), Newark, NJ 18.79” (old record 13.22” in Oct. 2005 although an unofficial 22.48” was reported from Aug 1843). Hurricane Irene also broke Newark, New Jersey’s all-time 24-hour precipitation with an 8.92” accumulation on August 27-28. Irene was the strongest tropical storm to strike New Jersey and New York since Floyd in September 1999.

The summer of 2011 has now officially been reported as the wettest in New York City history with a total of 25.23” (old record was 22.40” in 1975). Normal summer precipitation is 13.45”.

The coldest temperature measured in the northern hemisphere during August was a reading of -34.1°F (-36.7°C) at Summit station on Greenland on August 25th.


The warmest temperature measured in the southern hemisphere during August was 107.6°F (42.0°C) at Villamontes, Bolivia on August 11th.

Rainfall in the Atacama Desert of Chile has accumulated to .13” so far this year, six times above the annual average for this driest region on earth.


One of the most intense heat waves to strike southern Europe since 2003 spread from Spain into France, Germany, and Italy during mid August. An all-time record of 42.1°C (107.8°F) at Florence, Italy was recorded on August 22nd. See my blog of August 24 for more details on this heat wave. NOAA reported a temperature of 117°F (47.0°C) at Cape Carbonara, Sardinia during this heat wave as the absolute maximum temperature recorded in Europe for August.

Meanwhile, it was cool and rainy in most of northern Europe. In fact, England and Wales recorded its coolest summer since 1993 (this following the extraordinary warmth of the spring months!). The United Kingdom extremes for August included a maximum temperature of 86.5°F (30.3°C) at Gravesend, Kent on Aug. 3, a minimum of 34.5°F (1.4°C) at Loch Glascarnoch, Highland on the 25th, and a 24-hour maximum precipitation amount of 3.09” (78.6mm) at Malham Tarn, North Yorkshire on Aug. 10-11th.


Severe flooding hit the Nigerian city of Ibadan August 25-28 killing at least 25 people and displacing many thousands. It was the worst flood to strike Nigeria in “recent history” according to Red Cross officials. Flooding also affected the countries northern state of Bauchi killing 10 on August 21st.

Heavy rainfall in the eastern district of Bulambuli in Uganda caused landslides that resulted in the deaths of at least 29 on August 29th.


The heat wave that blasted the Persian Gulf region in late July continued into early August setting more national heat records in Iran, Iraq, and Kuwait. The hottest temperature in the world during August and the hottest reliably measured temperature on record for Kuwait occurred on August 3rd at Mitribah with a reading of 127.9°F (53.3°C). Only Death Valley, Lake Havasu City, Arizona, and Moen jo Daro, Pakistan have ever reliably have measured hotter temperatures elsewhere in the world. A national record of 127.4°F was recorded at Nassirya Ali Air Base in Iraq on the same day and a possibly reliable national record for Iran was set at Dehloran with a 127.4°F (53°C) reading as well.

Typhoons wreaked havoc in the Philippines, Taiwan, and Japan at various times during the month of August. These included Typhoon Muifa which struck Okinawa early in the month killing two and brought flooding rains to Korea killing an additional 10, Typhoon Nanmadol which stuck the Philippines killing 16 and Taiwan (where one death was reported) August 25-27th and then China near Shanghai on August 31 , and Typhoon Talas which struck Japan as a strong tropical storm on September 3rd. resulting in torrential rains that caused flooding resulting in the deaths of 32.

This chart outlines the tropical storm acitivity so far this year in the Western Pacific region. Graphic from Wikipedia.


Tasmania recorded its warmest August on record with temperatures averaging some 2.4°C above normal thanks in large part to exceptionally mild nighttime temperatures (see map).

Map showing the departure from normal for minimum temperatures across Australia during August. Courtesy of the Australian Bureau of Meteorology.

Precipitation was mostly normal across most of the continent.

The warmest temperature for the month was 99.5°F (37.5°C) at Noonamah, Northern Territory on Aug. 30, and the coldest 12.2°F (-11.0°C) at Charlotte Pass, New South Wales on Aug. 10. The heaviest daily rainfall reported was 5.57” (141.4mm) at Mount Victoria, Tasmania on Aug. 9th.


A rare blizzard struck New Zealand on August 14-15th dropping up to two feet of snow and closing airports. Just prior to this unusual polar blast, the AAO index values were among the most negative since NOAA's Climate Prediction Center records began in 1979. The index bottomed out at -4.728 on July 29th, 2nd lowest only to -4.855 on November 23, 1997.

Rare snowfall blankets Ohakune on New Zealand’s North Island on August 15th. Up to 25.6” (65cm) was reported from a location on the South Island and 20” (50cm) on the North Island. Photo by Zoltan Papai.

The snow first struck the South Island on Aug. 14th closing airports at Christchurch and then spread to the North Island on August 15th dusting the southern suburbs of Auckland with its first measurable snowfall since the mid-1970s. Auckland Airport recorded its coldest daily maximum temperature on record (records began in 1966 here) on August 15th with a high of just 46.6° (8.1°C) and Wellington a maximum of 44.2°F (6.8°C), their 2nd coldest daily maximum since 43.7°F (6.5°C) in June 1976. -yes it doesn’t actually get very cold in the beautiful cities of New Zealand!.

For New Zealand as a whole the cold wave and snow event was the most extreme since 1939.

Snowfall accumulations in centimeters reported across New Zealand during the storm of August 14-15th. Map from New Zealand Met Service.

Note the synoptic forecast chart for August 14 here from the New Zealand Met Service:

We can see that the amplitude that brought the record cold and snow to New Zealand also resulted in the record warmth in Tasmania, Australia as mentioned above in my Australia review.

Given that it was the amplitude of the upper air isobars in the northern hemisphere that resulted in the extraordinary temperature anomalies in the United States this past summer (and the relatively cool summer in northern Europe), I find it interesting that such amplitudes were almost duplicated in the southern hemisphere as well, at least in the southern Pacific region.


The coldest temperature in the southern hemisphere and the world during August was -105.2°F (-76.2°C) recorded at Vostok station on August 22nd.

KUDOS Thanks to Maximiliano Herrera for global temperature extremes data and Stephen Burt (no relation!) for the U.K. extremes.

Extreme Weather

Re-Cap of Summer of 2011 Heat Records in the U.S.A.

By: weatherhistorian, 5:33 AM GMT on September 05, 2011

Re-Cap of Summer of 2011 Heat Records in the U.S.A.: Perhaps one of the Four Warmest Summers Since 1895

The final data has yet to be compiled by the NCDC but the climatological summer (June-August) of 2011 is on track to be one of the warmest, if not the warmest, on record for the contiguous United States. It has, however, without doubt been the warmest for the South Central and Southeast (excluding the Florida Peninsula) regions. Here is a factual list of all the major sites (meaning those with a long period of record and of some metropolitan significance) that have just endured their warmest summer and/or their hottest-single-month on record. A list of all-time absolute maximum temperatures recorded is also included.

An Interesting Fact

San Angelo and Lubbock, Texas both recorded their single hottest month on record in June. Then in July those records in turn were broken. And then, in August, their July records were broken! In other words, in over 100 years of records for both cities, their three hottest-single-months were respectively, August, July, and June 2011. I do not believe this has occurred at any American weather station in recorded history.

Many sites, especially in the Southeast, recorded their warmest summer on record in 2010 only to have it broken this past summer in 2011. Given the long periods of record of these sites, this quite an accomplishment.

Phenomena of Endurance of Heat and Exceptional Warm Nights

It should be noted that it was not the actual extreme maximums of the heat that has been so remarkable this past summer but the endurance of the heat and the phenomena of many record high minimum temperatures. In fact, I will post a blog later on this subject since it seems to be an enduring quality of recent heat waves over the past years and deserves special attention.

The Data

Below are lists of all the important sites that:

1) Recorded their warmest climatological summer

2) Recorded their single-warmest month on record

3) Recorded their absolute maximum temperature

This list only includes the 303 sites that I follow assiduously since they all meet the criteria of long periods of record (POR), represent important population centers, and/or represent an important climate region or climate type (thanks to their altitude or geographic location). The sites represent where 90% of the nation’s population resides within a 50 mile radius of each location..

Below is a map of the sites I mentioned above. I have shaded the region that has just recorded its warmest summer on record. This represents about 15% of the contiguous United States (45 of my 303 stations).

Here is the list of some 45 (out 303) stations that have recorded their warmest climatological summer on record during this past summer of 2011:

Here is a list of the sites that have recorded their warmest single month on record (36 of 303 stations) during the summer of 2011. This may have been either during June, July, or August:

Here is a list of the sites that have either tied or broken their all-time absolute maximum temperatures during the summer of 2011:


So many heat records of various types have been shattered this past summer that it is impossible to quantify them. Many have to do with longest consecutive days with 100°+ or 90°+ temperatures or the aggregate of such. Suffice it to say that almost every site in Texas and Oklahoma broke such as well as portions of Arkansas and Louisiana. Furthermore, I have not mentioned the dozens of sites (from my list of 303 stations) that reported their 2nd warmest summer or 2nd warmest single month this past summer.

Not since the great heat waves of 1934 and 1936 has the United States seen so many heat-related records broken as occurred this past summer (not to mention last summer, 2010). The back-to-back nature of the intensity of the past two summers should raise some interesting questions, questions I am not qualified to address.

Later this month (around September 15th) we will have the final NOAA evaluation of this summer’s warmth relative to those past. The three warmest summers in the contiguous United States records (since 1895) were : 1) 1936 with a 74.6° nation-wide average, 2) 2006 with a 74.4° average and 3) 1934 with a 74.2° average. A mitigating factor this summer, however, is the fact that west of the Rocky Mountains the summer has been either normal or cooler than normal in places like Seattle, Portland, San Francisco, and Los Angeles.

Christopher C. Burt
Weather Historian


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Weather Extremes

About weatherhistorian

Christopher C. Burt is the author of 'Extreme Weather; A Guide and Record Book'. He studied meteorology at the Univ. of Wisconsin-Madison.

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