Showers/thunderstorms today and tonight precede heat/humidity
A warm front will be pushing east out of the central and northern plains, passing over our area tonight and early Saturday preceded by bands of showers and thunderstorms. Northern Illinois and northwest Indiana are positioned in a Marginal Risk for Excessive Rainfall during that period (dark-green-shaded area on the headlined map). Strong southerly winds gusting to 25 miles per hour will drive waves along the Lake Michigan shoreline, mainly off the Lake County, Illinois shore north along the Wisconsin shores where a Beach Hazards Statement calls for 3 to 5-foot waves along with rip and structural currents this Friday afternoon into the overnight hours (see greenish-blue-shaded areas on map below).
Heat and humidity will then ride gusty southwest winds into the Chicago area beginning Saturday and extending into the middle of next week. Daily highs in the 90 to 95-degree range along with dew-points in the 70s will support an extended period where heat index values could approach 100-degrees each day, especially Sunday through next Tuesday.