September temperatures were really a rollercoaster this year, setting 2 all-time records on September 7 and September 11, and then plunging down to a recent coldest-High on September 13. We started with roughly 2 really warm weeks, then had 2 really cold weeks, and ended the month on the warm side again.
With an average High temperature of 18.8°C, this September was about middle-of-the-pack. (and it just edged-out 1917, which had an average of 18.5°C)
It did have one day above 30°C - which is only the 3rd time that's happened in the last 20 years - and there were a total of 5 days above 25°C and 15 days above 20°C. But it also 4 days that didn't reach 10°C, and that's not unusual, but it is on the cooler side of things.
Just looking at the colours in this table, the heatwaves at the beginning of the month show up as the darker-reds, and the group of chillier days in the middle of the month are the more faded orange.
September Lows
As per usual, the Lows follow the Highs. We broke 2 records for all-time warmest-Lows on September 8 and 27, following the 2 records that were broken in August. 4 all-time records in 2 months might sound like a lot, but we took a closer look at that a few weeks ago in: How Often Does Edmonton Break Temperature Records?
The 0.9°C Low on September 15 was the coldest-Low on that day since 1995.
The average Low was 7.2°C which is pretty typical. About half of the time September will record some Lows below 0°C, but that didn't happen this year. The closest we came was 0.9°C on September 15.
Precipitation
Here we have the precipitation for the month, and with 66mm at the International Airport this September was well above the average.
In comparison this is another month where Blatchford was substantially below the International, recording only 45mm. So far in 2017 the International has recorded a total of 442mm of precipitation, while Blatchford is almost 100mm less at 344mm
This chart also shows 2016's precipitation for comparison, and it had a dry September with only 22mm, but then an above-average October at 37mm.
Snow
It feels strange to be talking about snow already, but I guess it's time.
In September 2017 the International recorded 8.4cm of snow, which is more than in any other year since 1995. The only other recent years with snow were 1999 with 2.4cm, 2004 with 5cm, and more recently 2014 had 4.4cm. Luckily September snow always disappears fairly quickly.
This chart also shows the snow from last winter, and there was no snow in September of 2016, but October 2016 had quite a bit with 22cm.
October Temperatures
As we head into October, things are going to cool off.
In September we had 15 Highs above 20°C, but in October about half of the time there won't be any. We'll definitely see some overnight Lows below 0°C and probably below -5°C. And about half of the time we'll see some daytime Highs that don't even break above the freezing mark - in recent years 2012 was the extreme example of that, with 10 daytime Highs below 0°C.
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