Weather
St. Louis, MO Weather: 107°F Heat Index Possible Tuesday Before Storms Bring Some Relief Wednesday
St. Louis, Missouri – Heat index values could reach 107 degrees Tuesday along and south of the Interstate 70 corridor, bringing another round of summer level heat to the St. Louis region while thunder
By Cameron Hayes · 2026-09-13T20:01:25.990Z
St. Louis, Missouri – Heat index values could reach 107 degrees Tuesday along and south of the Interstate 70 corridor, bringing another round of summer level heat to the St. Louis region while thunderstorms keep northern communities somewhat cooler.
According to the National Weather Service in St. Louis, Tuesday highs will range from 84 to 98 degrees across the bi state region, with heat index values between 91 and 107. Temperatures along and south of I 70 will generally climb into the 90s to near 100.
St. Louis and communities along the I 70 corridor should prepare for the greatest heat during the afternoon. Residents working outside should drink water frequently, limit strenuous activity during peak heating and check on people without reliable air conditioning. Children and pets should never be left inside parked vehicles.
Scattered afternoon showers and thunderstorms Tuesday will hold temperatures down across northern portions of the region, creating a sharp temperature difference across Missouri and Illinois.
Wednesday brings another chance for showers and thunderstorms, especially during the morning. Highs will range from 82 to 97 degrees, while maximum heat index values could still reach 104 in the hottest locations.
The heat will remain the primary concern south of the stormier areas through Wednesday, and residents should monitor National Weather Service alerts for changes in both heat and thunderstorm conditions.