National Weather Service United States Department of Commerce

Heat and humidity will gradually increase the rest of this week, with highs rising into the upper 80s to around 90 degrees by Friday. Lows will be in the upper 50s and lower 60s tonight, lower 60s Thursday night and in the 60s thereafter. Sunny to mostly sunny skies will prevail again on Thursday, with a few more clouds on Friday as isolated showers and thunderstorms possible Friday afternoon into Friday evening along and west of I-55.
Very warm and more humid conditions will highlight the holiday weekend, as afternoon heat index readings climb into the low to mid 90s each day. Isolated showers and thunderstorms will be possible Saturday, over southeast IL Sunday afternoon, and in eastern IL Monday afternoon. Most of the holiday weekend should be rain free with a fair amount of sunshine over central IL for outdoor activities.