The cool mornings in recent days may obscure for some just how warm this October has really been.
We’ll hit 74 degrees Tuesday afternoon. That’s not bad for a time of the year in which 61-degrees is the normal high. That’s 13-degree above normal!
The high temp was only 50 on this date (October 19th) a year ago, a reading 24-degrees cooler than today’s predicted high.
We’ve been treated to unseasonable warmth this month and for much of climatological autumn 2021. It’s a point driven home not only here but across a wide swath of the country, but nowhere more than across the nation’s midsection. (Sections of the West have been the exception).
In Chicago, since the start of meteorological/climatological fall 2021 on Sept. 21, we’ve had nearly four times the above normal days versus normal or below normal days temperature-wise: 38 days above normal; only 11 days below normal.
Put another way, 78% of our autumn days here have been warmer than normal.
Here are some additional facts on Chicago’s warmth to date this October and a few national facts on October 2021 versus October 2020:
- Chicago has recorded nearly twice the number of 70-deg and warmer temps in the opening 19 days of October, 2021 than was the case last year—–thirteen 70s this year versus 7 a year ago
- October 2021 when today’s predicted warmth is factored is running 8.8-degrees above normal to date and an eye-catching 9.5-deg warmer than a year ago
- 17 October 2021’s opening days have finished “ABOVE NORMAL”–That 89% of them
The warm autumn has Lake Michigan’s surface water temp, pegged at 62.7-deg by NOAA’s Great Lake Environmental Research Laboratory in Ann Arbor, MI—a reading 7.3-degree warmer than roughly the same point in the month a year ago
Nationally, snow covers just 2.7% of the Lower 48–all of that out in the sections of the Rockies. Snow coverage a year ago today (Oct 19) was 8.2% of the country. That means snow coverage last year on this date was three times the area covered this year.
Now keep in mind, all this can turn on a dime. It’s happened in the past. And we do have noticeably cooler air coming later this week and over the coming weekend—but nothing untoward for the time of year.
And with a La Nina now underway in the equatorial Pacific, there’s a history of cold season temperature volatility in La Ninas. In other words, wide temp swings as the Chicago area moves from Pacific air to arctic air. There’s a modest tendency for La Nina winters in Chicago to produce at least modestly above normal temps (58% of them have) and above normal precip (nearly 60% have done this). Whether that above normal precip falls as rain or snow will depend a great deal on the ultimate storm tracks and the actual winter temp trend.
Full forecast details at the WGN Weather Center
And it must also be noted that no two La Ninas are alike. Each has its own character which may end up flying in the face of past La Nina trends–so we have much to monitor in the coming weeks and months.