2017/11/24

The Cold November Rain?

We had a bit of a downpour yesterday, which raises the question: how often does Edmonton get rain in November?

Here's the answer:

This uses rain data from the International Airport, because the Blatchford weather station doesn't track rain separately from snow. We know that the International can be quite a bit colder than the city, and so there are probably days where the city had rain that aren't included here, because at the airport it fell as snow.

The only years since 1995 with no November rain at the airport were 2001 & 2003, and both 1995 & 1996 each only recorded 0.2mm. The average is 2mm, although that is skewed by 1999 with 9.1mm and the 8.6 last year in 2016.

This year on November 23 the International recorded 1.6mm, which makes it the 9th rainiest November day since 1995. It's the 3rd or 4th rainiest in the back-half of November though, because most of our November rain tends to happen early in the month.

Update:

For a bit more historical context, here are the Airport's November totals going back to the 1960s.

This chart shows the rainfall totals in blue, and the number of days with rain in green. The 5-year averages appear as dotted lines. And things haven't changed too much over they years.

For the rainfall totals the averages are skewed by the occasional Novembers that are really rainy. For the number of rainy days, since about 2007 the average has been a bit higher than it used to be - although that's a small difference of 3-or-4 rainy days instead of 2-or-3.

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