St. Louis, Missouri – Darkening skies, sticky air, and a growing flood threat are setting the stage for a potentially disruptive Sunday across the St. Louis metro area. What begins as a warm summer day could quickly transition into heavy rain, lightning, and localized flooding by afternoon and evening.
According to the National Weather Service in St. Louis, a Flood Watch remains in effect from Sunday morning through late Sunday night for portions of eastern Missouri and southwest Illinois, including St. Louis, St. Charles, Alton, Edwardsville, Union, Sullivan, Washington, and Vandalia.
Forecasters expect thunderstorms to develop during the afternoon as temperatures climb toward 85 degrees. Rain chances reach 90% Sunday afternoon and remain elevated into Sunday night. The concern is not just thunderstorms, but repeated rounds of rain moving across the same locations.
The National Weather Service warns that 1 to 3 inches of rainfall are possible, with locally higher amounts where storms repeatedly track. Streams, creeks, low-water crossings, and flood-prone roadways could see rapid rises.
Drivers on I-44, I-55, I-64, I-70, Interstate 270, and Highway 40 should prepare for reduced visibility, ponding water, and slower travel during heavier downpours. Plan extra time Sunday afternoon and evening. Never drive through flooded roadways.
Meteorologists are also monitoring the broader Midwest storm pattern. National guidance continues highlighting flash flooding concerns from the Plains into parts of Missouri and Illinois as moisture-rich air feeds developing thunderstorms.
Conditions improve Monday, although a lingering 20% storm chance remains before drier weather arrives Tuesday and Wednesday. Highs cool into the upper 70s Monday before rebounding into the lower 80s by midweek.
Residents should keep weather alerts enabled and monitor updates throughout Sunday. Additional warnings may be issued if storms intensify or flooding develops.
Five Day Forecast for St. Louis, Missouri
- Sunday: Thunderstorms likely, high 85°F, 90% rain chance.
- Monday: Slight chance of thunderstorms, high 79°F.
- Tuesday: Mostly sunny, high 82°F.
- Wednesday: Mostly sunny, high 84°F.
- Thursday: 30% chance of showers and thunderstorms, high 83°F.
