Between yesterday and todays's 80°+ highs we will see the first back to back 80s in about 7 months. O'Hare's 85° high Tuesday was the warmest we have seen in 230 days going back to the middle of last September. It felt just like July with temperatures 20° above average or what we typically see in the middle of summer.
The big question is how long will this last?
The answer is not very long, unfortunately.
A slow moving storm system will spin up clouds and showers (with a few rumbles of thunder) starting tomorrow and right on through the weekend. Winds off the lake will keep us cooler through early next week. The longer range forecast from the Climate Prediction Center outlooks most of the eastern part of the country for cooler than average temps (see image below).
It could always be worse. Snow will fall later today and into tomorrow from the Twin Cities in Minnesota through the northwoods of Wisconsin where up to a foot of spring snow could pile up. Record snowfall is possible in Minneapolis where the all-time record for a single storm's snowfall during the month of May is 3". The GFS model spits out just under 4" for Minneapolis between now and noon Friday but most other models are indicating a bit more than that (see image below).