2021 Heatwave Pre-cap: Part 1

Heatwave trivia will be in high demand during the next week, so let's take a quick look at Edmonton's history of heatwaves. In Part 2 we will see how Edmonton compares to some other Canadian cities.

Records Highs

The light orange line at the top of this chart is the record High temperature for each day from June 15th through July 15th. When this heatwave is over we will see how many records were broken, and how close we got to others.

At this time of year all of the record Highs are at least 30°C. June 24th and 25th are both at the low end right at 30°C, while for June 26th the record is 34°C. For June 29th the record is 37.2°C, which was Edmonton's warmest temperature on record.

30°C Days In-A-Row

For heatwaves, here is Edmonton's history of the longest stretches of days with Highs of 30°C or more. 

The record is 6 days, ending on June 7th 1961. Next up is July 1941 with a 5 days. And 4 days stretches happened in 1912, 1919, 1922, 1924, 1933, 1936, 1965, 1975, 2002 and 2008.

The Summer of 1961

These are what the Highs looked like for the summer of 1961.

The 6-day heatwave was at the start of June on the far left, and it set records on June 4, 5 and 6 which still stand today. That summer also had 3 other records which are still standing: June 15th, July 14th and August 15th.

The average High for June-August 1961 was 24.7°C, which ranks as our #1 warmest-recorded June-August. The #2 warmest was just a few years ago in 2015 at 24.6°C, and more typically the average is around 22.5°C. 

30°C Days Each Year

Edmonton isn't known for hot days, but on average we hit 30°C about 3~4 times per year. That average has gone up and down over the years, and it peaked in the mid-1930s at an average of 8 30°C days each year.

From year to year there is still a lot of variation though, with most years only getting 1 or 2 (2020, 2019, 2016, 2013), while others get more (2018 with 7, 2017 with 6, 2015 with 2015 with 9, etc). 

The year with the most 30°C days was 1961 with 14, which includes its 6-day heatwave. 2002 and 1933 both had 13.

35°C Days Each Year

The chart above shows the count of Edmonton's 35°C days, and it's a pretty bare chart because there have only been 5 of them.

• Edmonton's most "recent" 35°C was June 29, 1937 at 37.2°C. That was our warmest-ever recorded temperature, and our only day above 37°C.
• August 18, 1933 hit 35.6°C.
• July 1-3, 1924 had 3 35°C days in-a-row, with Highs of 35.6°C, 36.7°C (our 2nd warmest-ever day), and 35.0°C respectively.

So super-hot 35°C days don't happen very often (and haven't happened in 84 years) but:

• In recent years we hit 34°C in 2018, 2015, 2008, 2006, and twice in 2002.
• 32°C happens about every other year. Recently 2018, 2015, and 2009 had 2 of them; 2008 and 2006 had 3; and 2002 hit 32°C 6 times.

The Summer of 1937

Here we have the Highs for 1937, which included our warmest-ever day at 37.2°C. The day before that was a toasty 32.2°C, and the day after was down at 23.3°C. Overall 1937 was only our 48th warmest June-August.

The Summer of 1924

And for one more, here are the Highs for the summer of 1924. This included 3 35°C days in-a-row on July 1-3. Overall though this only ended up as our 78th warmest June-August, with lots of blue, below-average days from mid-July through the end of August.

So that is a quick primer on Edmonton's heatwaves. In Part 2 we will take a look at some other Canadian cities.