Summer heat and late autumn warmth
Good day to everyone!
It has been quite some time since I blogged but I must say I haven't stopped visiting this website. Quite the contrary, I come here almost every day. I have been waiting for a good subject worthy of a blog and this November's warmth for my area is certainly unheard of in the short 70 years of temperature record keeping for Montreal, Quebec.
Let's take a look at almost the only highlight of the last several months (the weather has been very bland but warm of late). This summer was absolutely beautiful. We saw an average July high temperature of 29C which is the hottest in 56 years making this month second only, since 1942, to the hot July of 1955 where the average temperature recorded was 29.8C. It seemed like every weekend was filled with sunshine and each month saw an average amount of rain.
One day in particular was very hot, tying the record for hottest high temperature in July and coming up short by only 1.5C to the hottest day on record which was set on August the 11th, 1944. However, records only start in 1942, therefore, there might have been hotter days before this said date...
Extreme heat of July 21th, 2011
It all started July 20th. The high of 32.7°C registered on my weather station matched the temperature of the hottest day of the month so far which was on July 11th. It's not uncommon to have a temperature in the low 30's celsius as two other heat surges during this month have peaked at a temperature of 32°C to 33°C. This heat surge was different, however. July 21th, a high of 35.8°C was registered making this the hottest day that I can remember. We've had times where the thermometer peaked at around 34°C for a couple of days straight but it's very rare to get to almost 36°C. The heat wave was felt in all of southern Ontario and extreme southern Quebec. Ottawa, Toronto and Windsor are but a few cities to have seen temperatures even higher. All-time highs were challenged in a lot of places.
Here are some numbers...
Ottawa
All-time July high: 36.7°C set on 21/1955 Difference: -0.4°C
All-time high: 37.8°C set on 08/11/1944 Difference: -1.5°C
Temperature on July 21th, 2011: 36.3°C
Toronto
All-time July high: 37.6°C set on 07/1988 Difference: +0.3°C
All-time high: 38.3°C set on 08/25/1948 Difference: -0.4°C
Temperature on July 21th, 2011: 37.9°C
Montreal
All-time July high: 35.6°C set on 17/1953 Difference: 0.0°C
All-time high: 37.6°C set on 08/01/1975 Difference: -2.0°C
Temperature on July 21th, 2011: 35.6°C
Windsor
All-time July high: 38.3°C set on 27/1941 Difference: -0.7°C
All-time high: 40.2°C 08/25/1988 Difference: -2.6°C
Temperature on July 21th, 2011: 37.6°C
Hamilton
All-time July high and all-time high: 37.4°C set on 07/1988 Difference: -1.0°C
Temperature on July 21th, 2011: 36.4°C
Sherbrooke
All-time July high and all-time high: 33.7°C set on 04/1983 Difference: -1.5°C
Temperature on July 21th, 2011: 32.2°C
Now on to the November warmth,
Figure 1: Shows trends of November average high temperatures since 1942 which I have made using Microsoft Excel and temperature records derived from the Environment Canada historical weather website.
The overall average temperature for the month was a balmy 9.8C (49.6F) when it should have been more around an average 5.3C (41.5F). That is a full 4.5C (8.1F) above normal! This breaks the old record set in 1948 by 0.7 of a degree Celsius. Incredibly, 4 of the top 5 warmest Novembers since 1942 have been felt after 1998. I bring you the top 5 (which can also be viewed on the graph above):
2011, 9.8C
1948, 9.1C
1999, 8.8C
2001, 8.6C
2009, 8.6C
Not surprisingly, December is also known for its warmth in the last 15 years or so. Without wanting to start a debate, I can almost guarantee that the melting of ice caps plays a large part in the warming of autumn and early winter in north america. Everyone knows the shrinking ice caps is causing the Arctic to warm up because of a decrease in the albedo effect and this most certainly affects us to the south as well.
Figure 2: Shows average temperature trends for the month of December over the years since 1942.
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