Extreme Heat Warning in Effect for Missouri and Illinois Through Wednesday
The National Weather Service in St. Louis, MO, has issued an Extreme Heat Warning and Heat Advisory for portions of Missouri and southwest Illinois. Heat index values are forecast to reach between 100°F and 110°F (37.8°C to 43.3°C) each afternoon through Wednesday, August 13, 2026. The most affected areas are between the I-70 and I-44 corridors. Forecaster confidence is high regarding the dangerous heat's impact, though the exact extent of the affected regions remains uncertain. The warning is set to expire at 8 PM Wednesday. 
