-5°C is a surprise

Today's chilly morning felt a little abrupt, which left me wondering how common temperatures of -5°C are for this time of year. And it turns out that this is pretty unusual.

Here's the recorded history of temperatures for October 6. I never expect us to set cold temperature records, since we can't possibly compete with the 1880s. But this chilly morning puts us in 12th spot overall, and 8th coldest in the last 100 years. In recent memory, 2000 hit -7°C, but before that we have to go back to 1970.

Looking at recent history, here is what's typical of the lows for this time of year:

We're in the area that's circled in red, and it's certainly not impossible, but it is unusual.

Here are all of the times in the last 20 years that the low has been -5°C or colder during the first two weeks of October:

And it's not all that common. 8 years out of 20 had a -5°C in the first 2 weeks of October, but only 4 years out have 20 have gotten that cold in the first week.

If we switch to the daytime high temperatures, it's the same idea.

Today we're supposed to reach 5°C, and that puts us is in the same well-below-average range as what we're seeing with the lows:

October 7 update:

And another cool morning on October 7th, at 4.9°C. That makes it the 5th coldest October 7th in 100 years, or 13th coldest overall.