St. Louis, MO – Unseasonable fall heat will grip the St. Louis region through the weekend, with highs near 90 degrees before a shift toward stormier weather early next week. The unusual stretch of summerlike warmth comes as the metro sits under an air quality alert, raising health concerns for sensitive groups.
According to the National Weather Service in St. Louis, Friday through Sunday will feature mostly sunny skies with highs from 87 to 90. Winds remain light, but ozone levels could climb, leading to poor air quality during peak afternoon hours. The alert covers much of eastern Missouri and western Illinois, including St. Louis, St. Charles, Madison, and St. Clair counties. Officials urge residents to limit strenuous outdoor activity and to carpool or use transit when possible.
Storm chances return Monday afternoon into Tuesday, with the best opportunity for scattered thunderstorms along I-70 and across the Metro East. The Weather Service notes a 40 percent chance of rain Monday, increasing overnight into Tuesday. Gusty winds and brief downpours could impact the evening commute.
Travelers and outdoor event planners should prepare for the heat this weekend, stay hydrated, and watch for possible lightning delays early next week. Public safety officials recommend checking on elderly neighbors, keeping pets cool, and avoiding leaving children in parked vehicles. Overnight lows stay mild, mostly in the 60s, until a sharp cool-down arrives midweek.
By Wednesday, highs drop back into the 70s with much lower humidity, bringing a refreshing end to the late-season heat wave.
Five-Day Forecast for St. Louis, MO:
Fri: 90/66 – Mostly sunny, light winds; air quality alert.
Sat: 87/61 – Sunny, warm; light south breeze.
Sun: 88/65 – Sunny; ozone concerns possible.
Mon: 85/66 – Partly sunny; 40% chance of PM storms.
Tue: 77/57 – Scattered showers, thunderstorms; breezy.
