Historical weather data, all-time temperature records, and monthly climate averages for Belleville, IL. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5 in Belleville typically lands you in that sweet spot of early spring — a comfortable 63° high with a 40° low overnight. The date has swung wildly over 77 years of records, from a scorching 88° in 1988 to a brutal 24° in 1970. Rain is a modest possibility at 31%, and snow is nearly off the table at just 1%.
Belleville plays hardball when it comes to weather extremes. The mercury has hit 110° on July 14, 1954 — one of the most punishing heat records in the region — and plunged to -27° on January 17, 1977. A single June storm in 1957 dumped 8.15 inches of rain, and a January blizzard in 1982 buried the area under 14.8 inches of snow.
Belleville runs hot and humid in summer, with average highs near 90° from mid-July through August — peak heat arrives the week of July 16. Winters are cold but not brutal, with the coolest stretch in mid-January averaging just 39°. June is your wettest month, so pack accordingly if you're visiting then, and expect a long, pleasant fall shoulder season through October.