Wednesday forecast: Warmest temps of the week in Chicagoland, increasing clouds later

Fall-like conditions continue around Chicagoland this week, with some locations recording temperatures in the upper 40s just before sunrise Wednesday morning.

But Wednesday is likely to be the warmest day of the week, with high temps reaching the mid- to upper 70s during the afternoon.

Morning sunshine will fade later Wednesday, however, as more clouds move into Chicagoland throughout the day, bringing a very small chance for isolated showers during the late afternoon hours for far western counties.

Wednesday night will be mostly cloudy, with a chance for scattered showers and even some rumbles of thunder, as temps fall into the lower 60s.

Scattered showers and possibly a thunderstorm will linger on Thursday, then clouds will decrease in the afternoon as highs reach the mid-70s.

Wednesday sunburn forecast

Chicago’s precipitation chances

There are only two periods of concern this week for anyone with outdoor activities planned. Late Wednesday night into Thursday brings the best chance for scattered showers and perhaps an embedded thunderstorm.

One model: How rainfall may lay out

The Thursday morning timeframe appears to the most likely period to see the best organized rainfall across the metro area.   

3 a.m. Thursday

6 a.m. Thursday

8 a.m. Thursday

10 a.m. Thursday

12:30 p.m. Thursday

Chicago forecast highs, how far from normal

Below-normal temperatures are projected to continue uninterrupted.

Friday looks like the coolest day, with highs more than 10 degrees below normal before some moderation over the Labor Day weekend. 

Forecast 500 mb height anomaly: Next 10 days

A strong ridge is forecast to move from western to central Canada, which leaves the door wide open for cooler air out of Canada to plunge into the eastern U.S. And it’s showing signs of staying power.

A sequence of negative height anomaly (troughs or pools of unseasonably cool air) over the Midwest will lead to below to at times much below normal temperatures into the open of September.  

Forecast temperature anomaly: Aug. 26-Sept. 1

Much below normal overall temperatures across the central U.S. to the Great Lakes and Northeast as we close out August and open September.   

Forecast temperature anomaly: Sept. 2-Sept. 8

While not quite as extreme as this week, the below normal temperature trend is forecast to continue for the first week of September across a large swath of the Lower 48, except for the Pacific Northwest, where late season heat is forecast to continue.  

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