First -20°C & -25°C of the Winter of 2019-2020

It finally happened: on January 9th we got our first -20°C Low of the winter, and then on January 10th the first -25°C showed up. How late were they?

"Technicalities"

First up, we just need to admit that while January 9th was the first -20°C of the winter, we came very close on November 11th at -19.6°C.

We will see today that January 9th is quite late for a -20°C, but November 11th was very early for a -19°C - the earliest since 2012, and before that 1995.

So -20°C is just an arbitrary cutoff, but we need to draw a line somewhere, so that's what we are going to talk about.

Recent -20°C Lows

Our first true -20°C Low was January 9th, at -24.2°C, and that is quite late in the winter. For 2010-2015 they all happened in November, but then 2016 was December 7th, 2017 was December 24th, and 2018 was December 30th.

Other recent winters which made it all the way to January without a -20°C were 2002-2003 on January 11th, 1997-1998 on January 1st, 1987-1988 on January 3rd. Those are all highlighted here:

One thing to notice about those winters is that even though they had a late -20°C, by the end of the winter they all still ended up with around 20 -20°C Lows. On average we get 22~25 so 1987-1988 and 1997-1998 we maybe a little bit below normal, but they still got most of a winter's worth of cold days, even though they started pretty late. A late start to winter does not necessarily mean a mild winter.

Ye olde -20°C Lows

Here we've gone back to the beginning of the records for comparison.

The winter of 1918-1919 made it all the way to January 1st for it's first -20°C, but for a lot of years they were in early-mid November.

1880-Today

And when we look at all of it together we can see the slow decline over the past century, from an average of about 50 -20°C Lows each winter down to about 25.


Recent -25°C Lows

Our first -20°C on January 9th was quickly followed by a -25.8°C on January 10th. That was also quite late.

Here we have a few of the other, recent, late -25°C lows.

On average we hit -25°C 8-10 times per winter. 2015-2016, 2005-2006, 1991-1992 & 1982-1983 were all well below that, but 2007-2008 & 2001-2002 both ended up around average, even with the late start.

The winter of 1986-1987 was the only one in Edmonton to not record a single -25°C.

1880-Today

Looking at the full history again, over the past century the average has dropped from about 25 -25°C Lows to around 8-10 now.