Turn off that air conditioner while you can, Chicago.
Come Thursday, temps could spike to between 98 and 101 with heat index readings climbing even higher, making it the hottest day of the season so far -- even hotter than last week's three-day heat wave.
Until then, abundant sunshine provides the backdrop for low humidity, calm winds and low 70s near the lake and 76 inland. Clear skies continue through Monday night as temperatures dip overnight to the low- to mid-50s in the west suburbs and 60 in Chicago.
NBC Chicago meteorologist Andy Avalos predicts heat levels will begin to rise Tuesday afternoon as a pleasantly cool morning gives way to lower 80s.
Wednesday conditions likely will become breezy, much warmer and slightly more humid. Afternoon highs could reach the upper 80s to lower 90s in the city and lakefront.
According to the National Weather Service, hot conditions are expected from Wednesday through Friday, and afternoon Thursday heat indices will get as high as 105 degrees.
Hot Thursday temps won't die down in predicted Friday rain. A few isolated thunderstorms are possible in the morning followed by moderately humid conditions and highs in the mid-90s.