National Weather Service United States Department of Commerce

Severe Thunderstorms in the Ohio Valley and Mid-Atlantic; Heat Continuing in the Central U.S.

Widespread strong to severe thunderstorms are expected from the Upper Ohio Valley into the Mid-Atlantic through Friday, with damaging winds as the primary threat. Dangerous heat will continue from the South-Central U.S. to the Midwest, Ohio/Tennessee valleys, and Mid-Atlantic. Widespread Major to Extreme Heat Risk is forecast into the weekend and will confine to the South-Central U.S. by Labor Day Read More >

So far this month, the high temperature in St. Louis has been 100, 100, and 99. That heat will remain in place through at least the first week of this month, and it looks like this will be one of the warmest starts to September on record.
An Extreme Heat Warning is now in effect for the entire region through Saturday. Afternoon heat index values will top out around 105 degrees. Please take precautions!
Very hot conditions will remain in place for at least the next week. The only relief on the horizon is when a weak cold front drops highs into the low 90s or upper 80s on Sunday, though that's still well above average for this time of year.