National Weather Service United States Department of Commerce

Rain begins to move in from the west late tonight. The best chances will be over central and northeast Missouri, where rain will be more widespread. Otherwise, most areas will skip in and out of showers on occasion.
After a few days of cooler weather to end the work week, heat and humidity is forecast to return this weekend and last into early next week. Right now, it appears that Sunday and Monday will be the hottest days with heat index values of 100-105+ possible each of those afternoons/evenings.