We're a little bit late this month, but now it's finally time for our big look back at Edmonton weather for September, 2023.
Was it warm or cool? Rainy or dry?
September 2023's average High of 19.8°C ranked as our 18th warmest overall.
The average Low of 8.4°C was 5th overall.
High Temperatures
The Highs for September 2023 were mostly pretty warm, although nowhere close to records or the top of our typical range.
September ends up with 22 Highs above average, and 8 below.
September averages about 11 Highs which reach 20°C, and 2023 had 16.
In 2022 we reached 30°C 3 times in September, but for 2023 the warmest was 26.3°C on the 11th.
The coldest High was 9.5°C on the 30th.
Hot Days
We're pretty close to the end of our season for hot days.
So far 2023 has had 115 days reach 20°C, which is the 5th most on record.
The long-term average was around 82.
We've had 56 days reach 25°C, which is the 5th most on record. That average is around 35 days.
We're probably done with really hot days.
2023 had 23 days reach 28°C, which is the 5th most on record. Recently 2022 had 24 and 2021 had 32.
And 2023 had 7 30°C days, which isn't unusual. 2022 had 11 and 2021 had 17.
Low Temperatures
It's pretty common for Blatchford to make it through September without a frost, but 2023 got close with 0.7 °C on the 30th.
We set 3 records for warmest Lows on September 11th, 12th & 23rd.
Overall September had 7 below-average Lows, and the rest were above.
2023 has now set new records for the warmest-Low for 15 days.
Recently 2022 had 11, and 2021 had 12, so in the past 3 years we've had 38 new record Lows.
2023 had another frost-free September. The last time that we had a September frost was in 2019.
First-Frost
Blatchford escaped a September frost, but Stony Plain had its first fall frost on September 30th, the airport's was the 19th, and Campsie's (100km NW) was the 6th.
Last year both Batchford and Stony Plain waited until October 23rd.
Warm & Cold Months
September 2023's average High was 2.8°C above the 20th century average, and is a medium orange bubble. So far in 2023 March was our only below average month.
The average Low was 3.8°C above the 20th century average, which is pretty warm, but not as warm as 2022's 4.8°C.
The Horserace
2023 might not have felt super-hot, but at the end of September the average temperatures rank as our 3rd warmest year on record, at about 2.1°C above the 20th century average.
The Highs are 1.8°C warmer, while the Lows are 2.5°C warmer.
Across Canada
September 2023's Highs were pretty warm across the country, ranging from 0.8°C above the 20th century average in Vancouver, to 4.7°C in Saskatoon & Regina.
The Lows were also warm, from 1.2°C above the 20th century average in Vancouver, to 3.8°C in Edmonton.
Across the country 2023 was not really a summer of super hot days.
For 30°C days Edmonton through Winnipeg were all around average, while Toronto, Ottawa & Montréal were low.
For 25°C days the Alberta & BC cities were high, while the other cities were average or low.
For 2023 so far the average temperatures are top-5 in Edmonton, Calgary & Montréal. Most of the other cities are sitting around the 15~25 range, with Winnipeg the coolest at #31.
Precipitation
On average in September we average 34mm of precipitation.
September 2023 was pretty dry, with 14mm at Blatchford, 18mm at the airport, and 32mm in Stony Plain.
In September we average around 10 days with rain. In 2023 the airport had 8 days, Stony Plain had 7, and Blatchford was down at 4.
The precipitation that we did get was pretty quiet, with the biggest day in Stony Plain with 15.9mm on September 28th.
By the end of September we average 383mm of precipitation for the year.
This year Blatchford is at 399mm, the airport is at 422mm, and Stony Plain is up at 450mm.
Precipitation Across Canada
This chart has the precipitation for 2023 for these 11 Canadian cities.
Halifax is at the top near 1,200mm, and Saskatoon is at the bottom at just above 200mm.
Vancouver, Calgary & Winnipeg are all having pretty low years.
(sometimes really low numbers mean that readings have been missed. But that doesn't seem to be the case here, with fairly complete records for the stations)
For big storms in September 2023 it's all Halifax, with 36mm on the 14th, and two more 20mm+ days. After that St. John's had the biggest storm with 14mm on the 19th.
October
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 14 freezing Lows.
October 22 is Blatchford's 2nd latest first-frost-of-autumn on record.
It just misses 2022's record of October 23rd.
1975 is 3rd, with October 21st.
2023 had a fairly early final-spring-frost on April 22nd, and a very late first-fall-frost on October 22nd. 
2023 snuck through on a bit of a technicality though, because we did already drop all of the way down to 0.1°C on October 1st and 5th. 
While Blatchford's first-fall-frost was very late this year, the rest of the region was closer to average, and got caught by some of the cool nights back in September.
Across the prairies Edmonton almost always records a longer frost-free season than the other big cities. 
October 22nd is an extremely late frost for Edmonton, but in central and eastern Canada it's just average.
St. John's had its first frost on October 18th, but the rest of the cities are still waiting.
This is another way of looking at how freezing Lows start to creep in during September & October. 
