Flash Flood Warning issued for St. Louis after 1 to 2 inches of rain

The National Weather Service issued a Flash Flood Warning for the City of St. Louis on July 4, 2026, after radar indicated thunderstorms producing heavy rain. The warning was set to remain in effect until 7:30 p.m. CDT, according to a City of St. Louis Emergency Management Agency notice.

At the time of the warning, the notice said between 1 and 2 inches of rain had fallen. It identified radar-indicated thunderstorms over Des Peres, an observation that supported the warning but was not a rainfall measurement for every part of St. Louis.

Roads and low-lying areas identified as risks

The warning covered the City of St. Louis and identified potential flooding impacts for small creeks and streams, urban areas, highways, streets, underpasses and other low-lying locations.

For a city with extensive paved surfaces and road infrastructure, the immediate concern in the notice was water accumulating in places where drainage can be overwhelmed during intense rainfall. The warning did not say that all parts of the city were flooded.

City emergency management advised motorists not to drive into flooded roads. That guidance was directed at the documented risk of flooding on streets, highways and underpasses during the warning period.

What the alert established — and what it did not

The alert was based on radar indications of thunderstorms and reported rainfall, rather than a complete gauge-based map of precipitation across the city. It documented an active flash-flood hazard and the locations considered vulnerable to high water, but it did not provide citywide flooding depths.

The available notice also did not establish total property damage, injuries or casualties from the July 4 event. Those outcomes should not be inferred from the issuance of a warning alone.

The City of St. Louis Emergency Management Agency’s posting reproduced the National Weather Service warning and stated its expiration time, but the available city notice did not specify the warning’s precise issuance time.

A separate July flooding episode

Later in July 2026, the National Weather Service’s St. Louis office documented a separate episode of catastrophic flash flooding in southeastern Missouri. The agency described a stationary front and repeated thunderstorms that led to flash-flood warnings across that part of the forecast area.

That later episode is distinct from the July 4 warning for the City of St. Louis. The July 4 notice should be understood as a single, time-limited urban flash-flood warning, not as evidence of a long-term climate trend or a finding about the later southeastern Missouri event.