Chicago, Illinois – Temperatures will climb into the 80s by Thursday afternoon, bringing a summerlike stretch of heat across Illinois and Wisconsin before a shift toward wetter and more active conditions.
According to the National Weather Service and NOAA’s Climate Prediction Center, both states are in a 70 to 80 percent probability zone for above-normal temperatures from April 16 through April 20. A broad heat dome across the Midwest will dominate early, allowing temperatures to steadily rise through the late week.
In Chicago and across Cook, DuPage, and Lake counties, highs are expected to reach 82 to 86°F between 2 p.m. and 6 p.m., with overnight lows holding in the mid to upper 60s. Farther north in Milwaukee and southeastern Wisconsin, highs will range from 80 to 84°F, slightly moderated by Lake Michigan but still well above seasonal averages.
Along the I-94 corridor from Chicago to Milwaukee, increasing southwest winds could gust between 25 and 35 mph at times, accelerating the drying of vegetation early in the period before moisture returns.
The precipitation outlook shows a 40 to 50 percent chance of above-normal rainfall developing between April 18 and April 22. Thunderstorm chances will increase across both states, with the potential for heavy rainfall, gusty winds, and localized flooding, especially in urban areas and along major travel corridors.
Residents should stay hydrated during peak heat, secure loose outdoor items due to increasing winds, and remain weather-aware as storms develop late in the period. Drivers should be prepared for sudden downpours and reduced visibility.
The most consistent heat is expected through April 18, followed by increasing storm chances into early next week. Additional advisories are likely as the pattern shifts from dry heat to a more active storm setup.
