Weather
Chicago, Illinois Weather: 90% Storm Chance Tuesday Night as Locally Heavy Rain Threat Builds Into Wednesday
Chicago, Illinois – Chicago area residents should prepare for a much wetter pattern by Tuesday…
By Natalie Rhodes · 2026-09-12T19:45:37.139Z
Chicago, Illinois – Chicago area residents should prepare for a much wetter pattern by Tuesday night, when thunderstorm chances climb as high as 90% and locally heavy rainfall could affect roads across northern Illinois and northwest Indiana.
According to the National Weather Service in Chicago, cooler weather arrives Sunday and continues into Monday before warmer, more humid air returns. Scattered showers are expected Sunday, followed by increasing thunderstorm chances Tuesday and Wednesday.
Sunday highs range from 70 to 80 degrees, with the coolest readings near the Illinois Wisconsin state line. Chicago and communities along Lake Michigan stay milder Sunday night, while inland lows could fall to 46 degrees.
Monday remains relatively quiet with highs of 71 to 77. A few showers could develop northwest and north central of Interstate 80, with additional showers possible late.
Conditions change Tuesday. Highs range from 79 to 92 degrees as humidity increases. Storm chances reach 20% to 70% during the day before climbing to 50% to 90% Tuesday night, when locally heavy rainfall becomes a concern.
Wednesday remains unsettled, with a 50% to 80% daytime storm chance and locally heavy rain possible. Drivers on I 90, I 94, I 80 and other Chicago area routes should watch for reduced visibility and water collecting on roads during downpours.
The wetter, stormier pattern could continue evolving into midweek, making additional National Weather Service updates important through Wednesday.