High Temperatures
Here we have the daily High temperatures for September 2019 compared to the range of temperatures for the past 30 years.
The month has ended with a coldsnap, with the 27th-30th all around 5°C which is right at the bottom of our range for September.
In the middle of the month we had 10 days of above average temperatures. Most of those days were around the 75th percentile and weren't extremely warm, but 10 straight "warm" days was more than we had managed all summer.
The little bargraph at the bottom of this dashboard shows how September 2019's Highs compared to other years. And 2019 is a little bit hard to see, because it's just a touch below the 30-year average. It is dwarfed by 2018 which was -6.5°C below average, and had the 3rd coldest Highs since 1880.
In September 2019 we didn't have any days hit 25°C, while the September average is about 3 days. We did have 12 days hit 20°C though, compared to an average of 10.
We also had 2 Highs below 5°C. That is less than the 7(!) we had last year during the ridiculously cold September of 2018, but most Septembers have none.
The average High for September 2019 of 17°C is right in the middle of the pack, and was similar to 2014-2016. It was a lot warmer than 2018's 11.1°C, but a lot colder than 2009's 22.6°C.
Low Temperatures
For the Low temperatures September 2019 was mostly just above average...right up until the last week when things took a nosedive. We had a few days right at the bottom of the 30-year range, but that is still above the coldest-since-1880 records which are down around -10°C.
The little bargraph at the bottom again shows how the Lows compared. September 2019's average Low was 1.4°C above the 30-year average, and was almost 5°C above 2018.
This September Blatchford record 3 frosts. That is down from the 8 we had in 2019, but it is a lot compared to most Septembers. In recent years we went frost-free in September in 2015-2017 & 2011-2012.
The average Low of 7.3°C was slightly on the warmer side of things - well above 2018, but also above 2014-2016.
First Frost
The first fall frost of 2019 on September 27th was 3 days after Blatchford's average of September 24th. That made the frost-free season for 2019 145 days long, from May 5th to September 27th, and that is right around average.
2019 So Far
After the cool summer there had been some hope that September would finally turn things around. It didn't really manage that though, with our average High for May-September coming in at 19.7°C. That was 0.7°C cooler than the 30-year average, and ranks 98th out of 139.
This chart can also be flipped to the Lows temperatures. The May-September average Low of 9.0°C was just -0.1°C cooler than the 30-year average.
Combining the Highs & the Lows, September 2019's Mean temperature of 12.1°C was 1.4°C warmer than the 20th century average for September. That makes this 2019's largest orange circle (or warmest month compared to the 20th century average) since back in March.
This chart can also be flipped to show the Highs or the Lows. For the Highs September 2019 is a small orange circle, at 0.1°C warmer than the 20th century average. For the Lows it's a large~ish orange circle at 2.6°C above the 20th century.
This set of charts can be a bit cryptic, but on a day-by-day basis it compares how warm or cold the year has been. The top section is for Mean temperatures, and then that is separated into the Highs and Lows.
For 2019 so far our mean temperatures are just a bit above the 20th century average at 0.34°C. In recent years 2018 was 0.9°C above the 20th century average, 2017 was 1.6°C, 2016 was 2.9°C, and 2015 was 2.6°C. The last year that was close to the 20th century average was 2009 at 0.2°C difference, and the last below-average year was 1996 at -1.7°C colder.
And while 2019's mean is sitting right now at 0.34°C above the 20th century average, the Highs are at -0.1°C below while the Lows are at 0.8°C above. We still have October-December to go though, and the winter months can really change things.
Precipitation
Switching over to precipitation, both Blatchford and the International were a little below the September average of 35mm. The International had 25.5mm and Blatchford had 24.2mm.
But even though our amount of precipitation was below average, our number of days with precipitation was a little bit above September's average of 10 days.
For the year so far Blatchford's total precipitation is a little bit above the average at 407.7mm, and the International is right around average at 373.8mm.
Snow
No snow!
Well, that's not quite right. The International reported "trace" amounts of snow on the 27th, 28th & 30th but they weren't enough to measure, so we're not counting them.
This chart has our history of September snowfalls for Blatchford (1880-2005) and the International (1960+).
2018 stands out with bubble after bubble after bubble for a record snowy month. But we also had significant September snow in 2017 and 2014, and one small snowfall in 2015. So in the last 5 years September snow has been quite common, but before that from 1992-2014 only two Septembers - 1999 & 2004 - had any snow.
We will talk a lot more about snow once it starts falling, but for today let's just look in awe at Calgary's 34.4cm of this September (which was all crammed into 4 days):
October Temperatures
Here's a look at what October could have in store for us.
We've mostly seen the end of our 20°C days, with October averaging only 1 per month. And we'll probably start seeing some below-freezing Highs, with October averaging 2 days below 0°C.
For Lows the frosts will undoubtedly start to ramp up, but October averages about 16 Lows above freezing.
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