Flood Warning Issued for Madison, IL and St. Charles, MO
If you are in immediate danger, call emergency services now.
For real-time, official alerts and instructions for your exact location, check weather.gov (US), weather.gc.ca (Canada), the Met Office (UK), or the Bureau of Meteorology (Australia) as applicable. This article is a data summary, not a substitute for the issuing agency's live warning.
Areazine synthesizes this NWS weather alert directly from NOAA's official public data feed. See our methodology for full source attribution and refresh cadence.
The National Weather Service has issued a Flood Warning for Madison, IL and St. Charles, MO, due to expected minor flooding on the Mississippi River at Alton from late Wednesday night to Sunday morning.
What this NWS weather alert tells you, and what most readers miss
This notice was issued by NOAA on May 10, 2026 and geographically references St. Louis Region. Its severity classification of "high" signals how the issuing agency weighs the risk of harm if no action is taken - "critical" and "high" tier alerts typically carry direct consumer actions, while "medium" and "low" tend toward informational guidance or monitoring advisories. The category it belongs to - Weather Alerts - determines the warning protocol behind it, which shapes what protective action (seeking shelter, following evacuation orders if issued, monitoring official updates) is recommended and which agency holds authority to issue or cancel it.
Most readers skim a notice like this, check whether they are personally affected, and move on. The more useful lens is to read it as a data point about the issuing system: how quickly NOAA detected the hazard, how precise the geographic or product-identifier scope is, and whether similar notices have clustered in the same category or region in the last 90 days. Cluster patterns frequently precede a broader regulatory action, a single localized NWS weather alert is isolated; three of them within a quarter often indicate a supply-chain, infrastructure, or seasonal driver that will keep producing notices until something structural changes.
For decision-making, Areazine pairs each alert with the original agency URL, the full agency name, and a timestamp so you can verify the notice against the primary source before acting on it. Tags on this item (weather, alert, Flood Warning, St. Louis) map to related alerts in the same area of risk - browsing them together gives a clearer picture than any single notice alone, because the shape of an ongoing issue only becomes visible across multiple sequential alerts.
Alert Details
The National Weather Service (NWS) St Louis MO has issued a Flood Warning. This alert is effective from April 30, 2026, at 3:00 AM CDT until May 3, 2026, at 7:00 AM CDT.
Affected Areas
The warning affects Madison, IL and St. Charles, MO, specifically including the Mississippi River at Alton, as well as other areas such as the Mississippi River near Herculaneum and at St. Louis.
What You Should Do
Residents should turn around and not drive through flooded roads, as most flood deaths occur in vehicles. Be especially cautious at night when flooding dangers are harder to recognize.
Expected Conditions
Minor flooding is forecast, with the river stage expected to rise above the flood stage of 21.0 feet early Thursday morning to a crest of 21.5 feet Thursday evening. At 11:00 AM CDT Tuesday, the stage was 18.2 feet.
Timeline
The alert is effective from April 30, 2026, at 3:00 AM CDT, and ends on May 3, 2026, at 7:00 AM CDT. It was sent on April 28, 2026, at 11:38 AM CDT and expires on April 29, 2026, at 11:45 PM CDT.
Original source: NOAA Official Notice ↗
Related Weather Alerts
All Weather Alerts →Frequently Asked Questions
Common questions about this NWS weather alert.