Historical weather data, all-time temperature records, and monthly climate averages for Forest Park, IL. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5th in Forest Park runs mild but unpredictable — expect a high around 55° and a low near 37°, though this date has seen everything from a balmy 78° in 2021 to a bitter 24° in 2018. There's about a one-in-three chance of some rain, but snow is essentially off the table.
Forest Park plays in the extremes — its all-time high of 104° in July 1999 and all-time low of -22° in January 2019 represent a brutal 126-degree swing. A single October day in 2017 dropped 5.2 inches of rain, and a December 2000 storm buried the area under 14.3 inches of snow.
Summers are the sweet spot, with highs peaking around 85-86° in mid-July, while mid-January bottoms out near 30°. If you're trying to dodge rain, avoid early May — that's historically the wettest stretch of the year at over an inch per week. Spring and fall offer comfortable temps but come with real precipitation chances.