October 2020 Review / November 2020 Preview

 We have lots to talk about for October 2020.

High Temperatures

October 2020 started-off pretty warm, but then it was cold-cold-cold, before warming back up to around average at the end of the month. We were well below average from the 16th through 25th, and that included 4 coldest-in-30-years Highs, but for that whole week-and-a-half we were right at the bottom of our typical temperature range. Overall the month ended up with 11 Highs above average and 20 below average.

Looking at the numbers, October started out with two Highs which hit 20°C. On average October gets about 2 of those each year, although October 2019 didn't have any. Then after the first week things rapidly cooled off, and we recorded 7 Highs that hit 0°C, including 3 that hit -5°C.

Highs of 0°C are pretty rare in October - we didn't have any in 2014-2017. And Highs of -5°C are very rare, with only 6 recorded since 2000, and 3 of those were this month. So that week-and-a-half coldsnap had some days which were very cold for October.

October 2020's average High of 6.9°C is on the cold side of recent years, but overall it was warmer than 2016 at 5.7°C or 2012 at 5.8°C.

2020 Warm Days

Unfortunately it's probably safe to assume that we have seen our final 20°C day of the year: the last time that we hit 20°C in November was 1949, although 2016 got really close hitting 19°C, 19.5°C and 19.9°C. 

2020 ended up with 100 Highs at 20°C. That's up from the 82 which we had in 2019, and is a little bit above the longterm average.

Low Temperatures

As usual the Low temperatures look similar to the Highs, with a warm start, really cold middle, and then warm~ish end. October 2020 had 15 Lows below average, which included 5 coldest-in-30-years Lows. But there were also 16 above average Lows, including 2 warmest-in-30-years Lows early in the month.

 

October 2020's average Low of -1.3°C was cool, but 2019 was cooler at -1.7°C, 2012 was -2.1°C, and 2002 was down at -2.7°C So it could have been worse.

We had 15 Lows below freezing, including 2 which hit -10°C, which is pretty unusual in October. Since 2000 the only Octobers to hit -10°C were 2002-2004, 2012, 2019 and now 2020 (although 2003 & 2003 both got all the way down to -16°C).

Frost-Free Days

Blatchford didn't record any frosts in September, and so our first frost of the year was October 9th. That's about 2 weeks later than average, and the final frost of spring on April 19th was also about 2 weeks early. So 2020 had 173 frost-free days, which is about a month more than average.

Dates of frosts vary wildly across the region, and so if you are interested in some of the other stations that data is here. 

Warm & Cold Months

October 2020 was definitely colder than average: the average High of 6.8°C ranks as #130 warmest out of 140, and the average Low of -1.3°C was #98 (to see that switch the chart to "Lows"). But it was still warmer than several recent Octobers: 2002, 2006, 2012 & 2016 were all in the bottom-10 for October Highs.

Over the years October's average High has stayed fairly constant around 10°C, or maybe even decreased a bit from 10.6°C. On the other hand the average Low has increased from around -9°C a century ago to -7.7°C today.

Sticking with the Highs, the cool October 2020 appears here as a fairly large blue bubble. But the row for October has several other fairly large blue bubble, because we have had a number of cool Octobers.

 

Across the Country

Looking across the county, October 2020 was pretty cold for the prairie cities, while in central Canada it was average~ish, and in St. John's it was a little warm.

How Warm is 2020 so far?

With two months left in 2020 it's time to check-in to see how the year's temperatures compare overall.

This isn't my favourite chart, but the red lines show how much warmer/colder the year has been compared to the 20th century average. Each time that the red line goes up that means the day was warmer-than-average day, and each dip was colder-than-average. It's broken into mean/high/low because our Lows are usually warmer than the longterm average, while our Highs are more variable.

For 2020 so far our cumulative average Highs are actually -0.05°C colder than the 20th century average, following the dip for the October coldsnap. The Lows have been 1.1°C warmer though, and so for the year as a whole we are at 0.53°C above the 20th century average, or the 49th warmest year since 1880.

Here we can see how 2020's overall temperature compares to recent years - the is the mean temperature, so it is the combination of the Highs & Lows. And right now 2020 is right in the range for a typical post-1980 year, although that could change drastically if November or December are much warmer or colder than average.

 

First Snow

The International Aiport recorded its first snow on October 16th. Looking back over the years that's a fairly typical date for the first snow, but it's much later than the really early September snowfalls that we had in 2014, 2016, 2017 & 2018.

Overall October 2020 recorded 4.9cm of snow, which is about half of October's average of 9.5cm.

A bit further south Calgary had another really snowy October with 27.9cm. That follows 15.8cm in 2019 and a record 48.4cm in 2018. Their October average is 12.1cm

Total Precipitation

For overall precipitation (snow + rain) October 2020 recorded 11.2mm at Blatchford and 12.5mm at the airport. Those were both low compared to the October average of 21mm.

October 2020 recorded 9 days with precipitation, which is right on the average. (I would have guessed that it was a gloomy month, but I probably think that of most Octobers)

2020's overall precipitation is still well above average thanks to the rainy summer, with Blatchford at 473mm and the International at 471mm. The average at the end of October is 407mm.

November Temperatures

We probably don't want to talk about November temperatures, do we?

On the plus side, November frequently still has a lot of Highs above freezing. Recently 2006 was down at only 7 and 2017 had 9, but plenty of years were up around 20 including 2018 & 2019.

On the less-plus side about half of the time November is when we'll see our first -20°C Low of the winter. November 2017 was pretty cold, but we haven't had a true November deepfreeze since 2014.