Aug 28 | Climate Review and Weather Update

by Trent Ford, State Climatologist
ISWS PRI University of Illinois

We had a lovely weather week, seemingly rare for this year. Average temperatures this week ranged from the mid-60s in northern Illinois to high 70s in southern Illinois, between 1 and 4 degrees below average. Lower humidity allowed for some very comfortable overnight temperatures, and even a few – dare I say – nippy early mornings. Some of the more impressive nighttime low temperatures this week included 49 in Elgin and 51 in Danville. Still, August has been right around 1 degree warmer than average statewide, with only a few days of summer left.

We also had a relatively quiet weather week, which was much welcome. Isolated thunderstorms dropped some impressive totals in pockets of southern and eastern Illinois, but most of the state had less than 1 inch of total rainfall this week. August to date is within 1 inch of normal for most of the state except for the area between Interstates 80 and 74, which has been 4 to 8 inches wetter than average this month. Summer 2026 will likely end much wetter than average in north-central and far southern Illinois, near normal in south-central Illinois, and somewhat drier than average in northwest and parts of southern Illinois.

Looking ahead, I hope everyone enjoyed the early taste of fall weather, because it’s about to get hot. Temperatures will quickly increase this weekend and into next week as the ridge over Texas opens and releases some very warm and humid air. Highs next week and into next weekend will regularly reach the upper 80s and low to mid 90s, while heat index values could spike over 100 degrees for several consecutive days. Forecasted temperatures for next week approach all-time records for early September. Meanwhile, the high humidity could fuel some isolated thunderstorms, but most of the state will stay pretty dry next week. So buckle up, summer is not done with us yet.