That Was One Warm September – for Oct. 8, 2009

Winnipeg

2009

24.0

11.4 17.7

Previous

24.5 1897

9.8 1931 16.8 1948

2009

24.6

9.0 16.8

Brandon

Previous

26.2 1897

7.8 1978 16.4 1897

2009

24.4

9.0 16.7

Dauphin

Previous

24.3 1891

9.3 1940 16.6 1940

No matter which way you slice it, September 2009 was one heck of a month weather-wise across the Canadian Prairies. After a year that saw summer struggle to get going, September moved in bringing plenty of sunshine and recording-breaking heat.

The warm, sunny weather actually started during the last couple of days of August as a ridge of high pressure developed over Western Canada. That ridge of high pressure dominated the weather until the last few days of September.

When I started looking at all the temperature records that were broken during September I noticed an interesting pattern. If we look at the number of daily temperature records that were broken, Alberta saw the greatest number, with over 50 stations breaking records. Next came Saskatchewan, with nearly 30 stations breaking daily records for heat. Finally, Manitoba pulled up the rear with only five records set for daytime highs.

From this you would think that when we look at the month as a whole, regions like Alberta and Saskatchewan would have broken their monthly records for the warmest September on record, but interestingly enough, this does not appear to be the case. I only looked at the temperature records for Winnipeg, Brandon, and Dauphin in Manitoba, Regina and Saskatoon in Saskatchewan, and Calgary and Edmonton in Alberta; but I felt these sites would give a good representation of the overall conditions for the three provinces.

When you look at monthly temperature records, there are three different values you can examine. The first is the average monthly high temperature, the second is the average low temperature, and the third is the overall average for the month.

In Alberta, only one of these records was broken and that was the average daytime high in Edmonton. During September, Edmonton saw an average daytime high of 23.3C which broke the 1967 record of 23.1C. In Saskatchewan, the number of monthly temperature records broken increased to three. Saskatoon saw its warmest overnight low temperature since recording an average temperature of 7.9C back in 1938. This year, the mercury averaged out at a balmy 8.3C for the average overnight low. In Regina, things were even warmer as the queen city broke two of the three monthly temperature records. Regina broke both the average daytime high record along with the average monthly temperature record. The previous records were set back in 1938 when daytime highs

averaged 24.8C and the average for the month was 16.5C. This year the same values were 25. 1C and 16.6C.

Finally, in Manitoba we saw even more monthly records broken. While I did look at three cities here compared to only two in the other two provinces, even dropping a city would still result in more records being broken. The easiest way to look at Manitoba would be to see which records were not broken. Dauphin broke two of the three monthly records by having the warmest daytime highs and warmest monthly average. Both Brandon and Winnipeg broke the records for warmest overnight lows and average monthly temperatures. The following table shows all the records for this region.

The biggest difference between Alberta and Manitoba was in the overnight lows. Alberta saw some fairly cool nights during September while Manitoba experienced some very warm nights (both Brandon and Winnipeg shattered their overnight low records).

Did September’s record warm weather make up for the cooler-than-average weather this summer? To be truthful, for a lot of growers it actually did. The late frost, combined with the warm temperatures, allowed for some crops to mature that never would have had it been a cold or even average September. For those of us who didn’t have to worry about crops, I think September’s weather almost made up for those nine months in a row of below-average

temperatures…but I think we will need a gentle end to the year to put those nine cool months totally behind us!

About the author

Co-operator contributor

Daniel Bezte

Daniel Bezte is a teacher by profession with a BA (Hon.) in geography, specializing in climatology, from the U of W. He operates a computerized weather station near Birds Hill Park.

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