The National Weather Service reports that Southern Illinois will experience unseasonably warm temperatures today (Thursday), with highs climbing into the upper 70s—well above the average for this time of year.
Rain chances are set to return Friday afternoon and overnight, mainly affecting areas north and west of the Ohio River. These showers and thunderstorms are linked to a broad upper-level system moving eastward, bringing a stalled front into the region by Friday night. While some scattered showers may persist into Saturday, significant rainfall is not expected until early next week.
The warm trend will continue, with high temperatures expected to remain in the 80s from Sunday through early next week as upper-level ridging strengthens. Forecasters say another round of rain could develop Sunday night into Monday morning, with additional chances Monday night through Wednesday. More substantial precipitation is possible across much of Southern Illinois by Tuesday night and Wednesday of next week.