September 2021 Review

It's time for our look back at the weather in Edmonton for September, 2021.

(if you are reading this in the distant future some of the dashboards below may have updated to reflect new data or formatting, or they may be broken, or they may no longer make sense. To see the original images for this post refer to this twitter thread.)

 
High Temperatures

September 2021 wasn't a hot month, but it also wasn't a cold one. 

23 days had above-average Highs, while 7 were below. 12.2°C was right at the bottom of our range, but the rest of the month (warm & cool) was pretty typical.

September 2021 had 3 days reach 25°C, which is right on the average. And we had 14 days reach 20°C, compared to a September average of 11. 

September also averages 3 Highs below 10°C, but this year the coolest was 12.2°C.

 
Hot Days So Far

Right now 2021 has had 50 days reach 25°C, which is the 9th most on record. That ties 2017, and is a bit below 2015 (52) and 2018 (55). 1898 has the record with 64. 

25°C Highs can happen in October, but are pretty rare.

 
Low Temperatures

For September 2021's Low temperatures, 19 were above average and 11 were below. September 11th's Low of 12.4°C was a new record-warmest. 

On the cooler side, the closest that we came to freezing was 1.2°C on September 24th.

September 2021 was frost-free at Blatchford, and that only happens about half of the time. 

On average September gets 2 freezing Lows, but there are years like 2018 which had 8, while others have 0 (2021, 2020, 2017, 2016, 2015...)

 
Frost-Free so Far

On average, Blatchford gets it's first fall frost on September 25th. So half of the time it's before that, and half of the time it's after. 

If you are a more risk averse gardener, September 17th is the 25% risk of frost, and September 10th is the 10% risk.

At stations around Edmonton, Stony Plain also hasn't had its first fall frost yet. 

But Namao's was on the 17th, St. Albert's was the 16th, and the Airport's was back on September 3rd.

Looking across the prairies, Regina's first frost was September 24th, compared to their average of the 16th. 

Calgary and Winnipeg have not had their first frosts yet, so this will be a late year for them.

 
Warm & Cold Months

The average High for September 2021 was 19.8°C, which ranks as the 16th warmest September on record. The average Low of 7.3°C was the 19th warmest. So this was warm month, but not a super-hot one.

In Edmonton June, July, August and September were all well above average. That also happened in 2017, 2016, 2012...

And if we look at the temperatures for June 1st through September 1st, 2021 is Edmonton's warmest on record. The average High of 23.7°C beats the previous 23.4°C from 1922. The average Low of 11.8°C beats 2012's 11.3°C.

 
Across Canada

September 2021 was a warm month in cities across Canada (except Vancouver). The Highs ranged for 4.1°C above average in Winnipeg, to 2.6°C for Calgary, to 1.3°C for Ottawa, to Vancouver right at the 20th century average.

And across Canada the average Highs for June 1st through September 30th were:

• #1 warmest on record in Edmonton and Winnipeg 
• #5 in Calgary and Regina top-10 in Toronto, Ottawa and St. John's 
• And for Vancouver it was 13th warmest, and 26th for Montréal.

How Warm is 2021 So Far...?

With 3 months left in 2021, right now it ranks as Edmonton's 6th warmest Highs on record, and the 13th warmest Lows. Combining those, this is 8th warmest year, with average temperatures 1.86°C above the 20th century average. Winter can change all that, though.

Across the country the Jan-Sep Highs for 2021 rank as:

• top-5 for Montréal and Winnipeg 
• top-10 for Edmonton, Toronto, Ottawa and St. John's 
• And this is #11 for Regina, #16 for Calgary, and #26 for Vancouver.

Precipitation

After a very dry summer we finally got some rain in September. In September we average 35mm of precipitation. Blatchford and the airport were a bit below that with 30.9mm and 24.9mm respectively. For Stony Plain, a big 42mm storm on September 1st pushed it to 66.5mm.

For 2021 so far, the Edmonton area is well below average for precipitation. Blatchford's 200mm is it's 2nd lowest year since 1880. Data for the Airport and Stony Plain only goes back to the 1960s, and this is a bottom-5 year for both of them.

This chart is messy because it has 9 Canadian cities:

• Edmonton is down at the bottom with 200mm.
• Calgary, Regina and Winnipeg are around 275~300mm.
• Vancouver. Toronto, Ottawa and Montréal are all 540mm~625mm.
• St. John's is way up at 988mm.

 
No Snow

Also, September had no snow. Recently the average date of our first snow is around October 6th, but 2018, 2017, 2016 and 2014 all had September snow. Lasting snow usually doesn't start to hang around until about Novermber 1st.

 
October Temperatures

For October, we average about 1~2 Highs of 20°C, but half of the time there are none. October also averages 2 Highs below 0°C, and 13 freezing Lows.

(and the airport averages 10cm of snow in October)