St. Louis Sizzles at 92 Before Brief Cooldown, Bigger Heat Wave on Tap

St. Louis is starting Wednesday, August 26, under mostly cloudy skies near 72 degrees, but the calm morning is a brief prelude to a hot afternoon. Temperatures are expected to climb to about 92 degrees, with mostly sunny skies and a light southwest breeze. The bigger change arrives later, when a cold front brings a small chance of showers or thunderstorms before a cooler, drier stretch takes over.

Hot Afternoon, Limited Storm Threat

According to the National Weather Service in St. Louis, the metro should remain mostly dry, with a 10% chance of rain Wednesday. Isolated to widely scattered showers or thunderstorms could develop from midafternoon into evening as the front moves southeast, with the best chance east and southeast of St. Louis, especially in south-central Illinois.

Any storm that forms could produce a quick downpour and gusty, potentially damaging winds, although the risk is conditional and no watches, warnings or advisories are posted for Missouri or Illinois in the current forecast. Winds will shift from southwest to northwest behind the front, generally staying between 2 and 8 mph. For outdoor plans, the practical concerns are the afternoon heat and a need to check the sky later in the day, not an all-day washout.

Cooler Thursday And Friday

Once the front clears, Thursday looks sunny and noticeably more comfortable, with a high near 87 and a low around 66. Friday stays sunny near 86, with a low around 65 and lighter humidity. That two-day break is the nicest part of the extended forecast, weather’s brief attempt at an apology.

Summer Heat Returns Sunday

Heat rebuilds over the weekend: Saturday is forecast to reach 89, Sunday 94, Monday 96 and Tuesday 95. Overnight lows also rise from the mid-60s late week to the mid-70s early next week. NWS forecasters say humidity should increase by Tuesday, when heat index values may approach or exceed 100 degrees, so outdoor plans will need more attention to water, shade and breaks.

For Wednesday, the most comfortable window for errands and outdoor activity is early, before the afternoon peak. Keep an eye on updated alerts if you’re east of the metro or traveling into south-central Illinois, where storm chances are higher later in the day. No official weather alerts are in effect for the St. Louis area as of Wednesday morning.