Illinois, Missouri Severe Extreme Heat Watch | Effective 06/26/2026 23:59

Headline: 
Extreme Heat Watch issued June 27 at 1:59AM CDT until July 3 at 12:00AM CDT by NWS St Louis MO
Event: 
Extreme Heat Watch
Urgency: 
Future
Effective: 
June 26, 2026 - 11:59pm
Expires: 
June 27, 2026 - 3:00pm
Description: 
* WHAT...Dangerously hot conditions with heat index values of 105 to 110 possible. * WHERE...In Illinois, Madison IL, Monroe IL, and Saint Clair IL Counties. In Missouri, Jefferson MO, Saint Charles MO, Saint Louis City MO, and Saint Louis MO Counties. * WHEN...From Sunday afternoon through Thursday evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events.
Instruction: 
Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.
Area Description: 
Madison; St. Clair; Monroe; St. Charles; St. Louis; St. Louis City; Jefferson
Forcast Office: 
NWS St Louis MO