Analyzing the hot summer on the Prairies

Precipitation so far in July has been light to non-existent

Analyzing the hot summer on the Prairies

It has been a hot summer so far this year across the Prairies with several locations breaking all-time heat records. There are several ways to look at temperatures and heat waves and one way I thought we could examine them is to look at the number of days with temperatures above 30 C and above 35 C we have seen so far this summer. While I will discuss these numbers here in this article, sometimes people find it easier to look at the data in the form of a table. So with that in mind, here you’ll see a table of data for the main reporting centres I use across the Prairies.

The table includes all of June and up to July 15. I have included the number of days each station has reported above 30 C and 35 C, along with the average or “normal” number of days we would usually see for the entire month. I also included the maximum and minimum temperature recorded each month along with the mean monthly temperature.

Where to start? I am going to concentrate mostly on Manitoba but will make some references to both Saskatchewan and Alberta and will mostly look at the number of days above the two threshold values. Starting in June, you can see that on average, southern Manitoba will see about 2.5 days above 30 C. This value is an average of the three sites, but the number of days only varies by about one day between them. The same is true for Saskatchewan and in Alberta, I used an average between Calgary and Edmonton. All locations across the Prairies easily surpassed the average with both Winnipeg and Calgary reporting nine days. This number is particularly impressive for Calgary as it usually only sees one day above 30 C in June.

Looking at the 35+ C days, you can see that we do not usually get that hot in the summer. For Manitoba, we would typically see one 35+ day about once every two years. So, while we “only” had a couple of 35+ C days, that is about four times what would be expected. The one value that jumped out at me in this area was Peace River, which saw three 35+ C days. On average it usually never sees a day warmer than 35 C in June, so to have three is amazing.

Looking at July, at first glance the numbers are not that impressive, but those values only represent half the month. With a warm to hot two-week outlook, I am sure these values will end up being much higher. Understandably, the number of 30+ C days for Manitoba goes up in July compared to June with the average being four days. What I find interesting is the number of 35+ C days goes down to 0.1 day or about once every 10 years. You would think that July, being warmer than June, would see more 35+ C days.

For this to make sense you need to think about humidity. The more moisture there is in the air, the more the sun’s energy must go into heating up that moisture and not heating up the air. That is why it gets so darned hot across a desert and not in humid tropical locations, even if they are at the same latitude. July is usually our most humid month as plants are in full growth mode, transpiring huge amounts of moisture into the air. Trouble is, this year we are in a drought, and we are not seeing much in the way of humidity. This allows the temperatures to really warm up, so I would not be surprised if we see a few more days 35 C or warmer during the last two weeks of the month.

The last value I included in the table was precipitation (PPT). Rainfall amounts in June, while not huge (with the exception of Brandon), were not that bad either. July has been a whole different story. For most locations amounts have been light to almost non-existent. There have been a few small thunderstorms, so some isolated areas have seen some good rains but overall, it has been very dry. Combined with the hot weather and low humidities this sets the stage for possible temperature records in the weeks ahead.


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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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