August 2025 Review & The Great Heatwave of August 2025

It's time for our big look back at Edmonton weather for August 2025. August has 31 days, but we're going to talk a lot about the final week. The word "unprecedented" gets thrown around a lot, but the end of August gave us a truly unprecedented heatwave.

August 2025's average High of 25.7°C was the 4th warmest on record. That's obviously hot, although recently 2022 got to 2nd spot with 26.6°C.

The average Low of 12.9°C was the 9th warmest. And again, that's warm. But it was actually below 2024, 2023 & 2022.





High Temperatures

August 2025 started warm, but then was maybe a little cool for a few weeks. 

But it ended with 8 straight 28°C Highs, 8 of which got to 30°C, and 4 of which got to 32°C. 

Overall there were 8 below-average Highs compared to 21 above-average, including 4 new records.

August averages around 10 25°C Highs, and 2025 had 19. 

That included 8 30°C Highs, when the average is around 1. 

The hottest was 33.3°C on the 27th. The coldest was 13.1°C on the 15th.





The Great Heatwave of August 2025

So what made this heatwave unique?

Our 30°C season can last from May-September, but it peaks in mid-July. From around June 22-August 18 is when we're most likely to reach 30°C. By August 25 we can still get there, but we're definitely out of the peak time.





Hot Days In-A-Row

The August heatwave gave us 6 30°C Highs in-a-row. That's the longest for this late in the year, and is 1 short of the all-time record set in July 2024 and July 2021. For late-August the previous record was only 3, and 2025 doubled that.

The August heatwave also gave us 4 32°C Highs in-a-row. That ties the all-time record from July 2021 and June 1961. And it also doubles the previous late-summer record, which was only 2 in-a-row.





Record Highs

We set 4 new record Highs in-a-row, from August 26th-29th. Those ranged from 32.2°C to 33.3°C, and were the 4th, 6th, 8th & 9th warmest temperatures ever recorded this late in the year.

Overall, 2025 now has 6 new record Highs. That's fewer that 2024's 11, but more than the 5 for 2021-2023. 

Just for the summer months of May-September, since 2021 we've set 29 new records, or about 20% of all of the days.





Hot Days So Far

The previous August record for 30°C days was 7, in 1967 & 1932. But 2025 sets a new record with 8. 

August 2025's 4 32°C days is also a new record, ahead of 3 in August 2008 & 1981. The 2 33°C days also tie 1922's record.

At the end of August, so far 2025 has had 14 30°C days. That ties 1964 for 3rd most ever recorded.

The only years with more? 2024 had 16, and 2021 had 17. (and with the forecast for September, we might catch them?)



Low Temperatures

And the Lows? Compared to the Highs they were a bit boring. For other recent heatwaves we had a lot of record-setting Lows, but August 2025 was warm without being flashy. 21 Highs were above-average and 10 were below.

August averages 4 Lows over 15°C, and 2025 had 7. But those were all early in the month. During the big heatwave dropped to around 12-14°C overnight.



The Horserace

How does the heatwave affect 2025's overall temperatures?

The mean temperature was already around top-20, and 1.5°C warmer than the 20th century average. 

August's hot week is visible here with the red line climbing upwards at the end, to around 13th warmest overall.



Warm & Cold Months

August 2025's average High of 25.7°C was 3.7°C warmer than the 20th century average, so it gets a medium orange bubble. But 2022 was warmer overall.

The average Low of 12.9°C was 3.3°C warmer also gets a medium orange bubble, similar to 2022-2024.



Across Canada

August 2025 another mostly above-average month across the country...except for Winnipeg. 

Kelowna & Edmonton were at the top, with Highs more than 3.7°C above their 20th century averages. 

Winnipeg was at the bottom, and -0.2°C below theirs.

One of the weird quirks of Edmonton's recent heatwaves is that this is the 2nd summer in-a-row where we've had as many (or even more) 30°C days than Winnipeg.



Precipitation

August averages 52mm of precipitation, which is our 3rd highest month.

In 2025 Blatchford was down at 28mm, Stony Plain got 44mm, the airport got 61mm, and Campsie (100km NW) got up to 114mm.

The big difference between the stations was the Blatchford's biggest day was only 11mm. The airport had 2 days around 15mm, and Campsie had 3 over 20mm.

By the end of August we average around 345mm of precipitation for the year (about 80% of our yearly total).

The airport and Campsie are right around average, while Stony Plain is at 266mm, and Blatchford is down at 248mm.



Precipitation Across Canada

These are the precipitation totals for 2025 across the country. Quebec City is still way out ahead with over 800mm. Montréal, St. John's & Halifax are over 600mm. Calgary is at 423mm, while Edmonton and the other prairie cities (also Kelowna & Victoria) are below 250mm.

Across the country the biggest August storms were: 

• Halifax & Vancouver over 40mm 
• Ottawa around 35mm 
• Quebec City, Toronto & St. John's around 25mm

September

For September we average 11 days at 20°C, including 3 at 25°C. And 2024 & 2022 both started with heatwaves.

For Lows, about half of the time September is frost-free, but right now our last September frost was 2019.