Current Conditions

When you walk outside in Chicagoland on Thursday, don’t adjust your calendars — it’s still almost two months to Halloween.

Yes, it is early September and therefore still technically summer, but the air certainly has an October chill to it Thursday morning, and it’ll remain cool throughout the day.

After the day started in the upper 40s to lower 50s around Chicagoland, high temps will only reach the mid- to upper 60s, the coolest temps in Chicagoland since late May.

In fact, the forecast high temperature map would be right on par if the calendar read Oct. 9. The normal high for Sept. 4 is 80 degrees.

There will be a good amount of sunshine, but jet stream winds blowing in from the northern reaches of North America will produce rather vigorous cooling, with winds gusting to 20 miles per hour Thursday.

The cool conditions look to remain in place through Friday and into the coming weekend, but temps are projected to rise back to at least near seasonal levels again by early next week (see more below).

The Next Few Hours

Thursday: Late afternoon temps, departure from normal

As cool as conditions will be locally Thursday, it will be even colder across the Northwoods, with highs only reaching the 50s, a level about 20 degrees below normal.

Thursday sunburn forecast

Extended Outlook

A reinforcing shot of cool air arrives, with clouds and perhaps a few sprinkles or a brief shower in Friday’s predawn hours. This marks the only threat of additional rainfall for the next week.

Model forecast: 2 a.m. Friday

Model forecast: 4 a.m. Friday

Model forecast: 7:30 a.m. Friday

The cool air will continue to be accompanied by a period of gusty winds, especially Friday morning, when gusts could reach 30 to 40 mph at times.

Forecast peak wind gusts: 1 a.m. Friday

Forecast peak wind gusts: 5 a.m. Friday

Forecast peak wind gusts: 8 a.m. Friday

Forecast peak wind gusts: 3 p.m. Friday

Chicago forecast highs, departure from normal

A string of well below normal days begins Thursday afternoon, continuing a streak that currently stands at 11 days in row through Wednesday.

From the Midwest to the Northeast, below normal temperatures will be in firm control:

Forecast mean maximum temperature anomaly: Saturday, Sept. 6, through Wednesday, Sept. 10

Break in the chilly pattern?

The 850-millibar temperature anomaly (one mile above the surface) is a good proxy indicator of how temperatures at ground level will respond. The blue shading represents cooler than normal, while the orange and red depict areas of warmer than normal.

This analysis of the 850-millibar temperature departure from normal indicates that a definite pattern change to much warmer weather is on tap, starting in the middle of next week into the following weekend.

But there are some unseasonably cool days to get through before that happens.

Current Conditions