St. Louis, Missouri – One final day of intense heat and humidity is expected across much of Missouri Tuesday, especially along and south of Interstate 70, before a much cooler and less humid air mass arrives Wednesday. A few thunderstorms developing this afternoon and evening could produce gusty winds before the refreshing change settles into the region.
According to the National Weather Service in St. Louis, heat index values will climb to 100 to 110 degrees Tuesday across areas along and south of I-70, where afternoon high temperatures will reach 88 to 98 degrees. A 30% to 50% chance of showers and thunderstorms is expected during the morning, increasing to a 40% to 70% chance during the afternoon and evening across southwest Illinois and southeast Missouri. The strongest storms could generate locally gusty winds.
Communities including St. Louis, Columbia, Jefferson City, Farmington, Rolla and surrounding areas should take precautions against dangerous heat during the afternoon. Drivers may also encounter brief periods of heavy rain and gusty winds as thunderstorms move through, particularly during the evening commute.
Residents are urged to limit strenuous outdoor activity during the hottest part of the day, drink plenty of water, wear lightweight clothing and check on older adults and those without reliable air conditioning. Never leave children or pets inside parked vehicles, even for a short time.
A much more comfortable weather pattern arrives Wednesday, with afternoon highs cooling into the upper 70s to mid-80s and noticeably lower humidity continuing through the end of the workweek. Another 40% to 60% chance of showers and thunderstorms is expected Friday, primarily along and west of the Mississippi River.
Five-Day Forecast for St. Louis, Missouri
- Tuesday: High 88–98°F | Heat index 100–110°F. Morning storm chance 30–50%, increasing to 40–70% during the afternoon and evening. Gusty winds possible.
- Wednesday: Mostly cloudy. High 78–85°F, Low 63–70°F.
- Thursday: Partly sunny. High 78–83°F, Low 58–65°F.
- Friday: High 75–80°F, Low 58–65°F. 40–60% chance of showers and thunderstorms, mainly along and west of the Mississippi River.
