St. Louis, Missouri – A relentless heat wave returns to eastern Missouri Monday, July 21, as temperatures climb to 94°F with heat index values reaching 107°. The National Weather Service has issued an Extreme Heat Warning through 7 p.m. Thursday, impacting the entire St. Louis metro area and surrounding counties.
According to the NWS, Monday’s heat will be accompanied by light winds, followed by a 20% chance of thunderstorms Monday night. Residents along the I-64 corridor, especially in Brooklyn, Illinois, and St. Louis County, should limit outdoor activity between noon and 6 p.m. and stay hydrated. Power grid strain and pavement buckling remain possible due to sustained highs near 100° through midweek.
Tuesday brings no relief, with mostly sunny skies and a high of 97°F. Overnight lows will offer minimal cooling, staying close to 78°F. Wednesday could mark the week’s peak, with highs near 99°F under mostly clear skies — a dangerous setup for those without access to cooling centers.
Heading into the weekend, temperatures will hover in the upper 90s. Isolated thunderstorms return Friday and Saturday, with minor relief in sight but continued health risks for vulnerable groups.
Five-Day Forecast for St. Louis, July 21–26:
- Monday: High 94°F, heat index up to 107°, slight chance (20%) of evening storms
- Tuesday: Sunny, high 97°F, low 78°F
- Wednesday: Mostly clear, high 99°F, low 79°F
- Thursday: High 99°F, mostly sunny, low 78°F
- Friday: High 97°F, 20% chance of afternoon storms
- Saturday: High 97°F, 20% chance of scattered thunderstorms
⚠️ Heat warnings remain in effect until 7 p.m. Thursday. More advisories may be issued midweek as storm chances increase.
