No active National Weather Service alerts for St. Clair County right now. This page is the live destination for St. Clair County (county seat: Port Huron) — bookmark it to check active watches, warnings, and advisories from NWS Detroit/Pontiac, plus regional context, common weather hazards, and the most recent alerts.
Southeast Michigan — the Metro Detroit region — combines the highest population density in the state with significant severe-weather exposure. Wayne, Oakland, Macomb, Washtenaw, Livingston, and surrounding counties face frequent severe thunderstorms, occasional tornadoes (most notably in Washtenaw and Lenawee), winter storms that can paralyze freeways, and growing concern about urban flash flooding as drainage infrastructure ages. Lakeshore flooding affects Wayne, Macomb, Monroe, and St. Clair counties along Lakes Erie, St. Clair, and Huron.
St. Clair County is served by NWS Detroit/Pontiac, headquartered in White Lake, MI, which issues all official severe-weather watches, warnings, and advisories for the county under the SAME geographic code MIC147. Alerts shown above come directly from the National Weather Service public-alerts feed and update within seconds of issuance.
The U.S. EPA's Safe Drinking Water Information System lists 104 public water systems in St. Clair County with open health-based violations or recent enforcement activity. These are typically municipal water utilities, mobile-home parks, schools, and private community systems — not bottled water or private household wells. Residents on these systems should have received a Consumer Confidence Report (CCR) by mail; the systems below are listed in order of open violations on file.
Based on St. Clair County's southeast lower peninsula (metro detroit) geography, residents and visitors should be prepared for these recurring weather threats:
A Tornado Warning means a tornado has been sighted or indicated by radar in St. Clair County or an adjacent area — take shelter immediately. Move to the lowest floor of a sturdy building, away from windows, and into an interior room (basement, bathroom, or closet). Mobile homes and vehicles are not safe; if you're in either, leave for a sturdy structure if you can do so safely. Tornado Warnings are typically issued for 30–60 minutes; stay sheltered until the warning expires or NWS Detroit/Pontiac confirms the threat has passed. St. Clair County residents should monitor a NOAA Weather Radio (programmed for SAME code MIC147), local TV, or this page.
A Flood Warning means flooding is occurring or imminent in St. Clair County. Do not drive through flooded roads — most flood-related deaths in Michigan occur in vehicles attempting to cross water. If you live in a low-lying area near Port Huron or along major waterways in the county, monitor official water-level reports from the U.S. Geological Survey and prepare to move to higher ground. Flash Flood Warnings carry the same urgency on a shorter time horizon — typically less than an hour to act.
Winter Storm Warnings in St. Clair County indicate hazardous winter weather (heavy snow, freezing rain, sleet, or blizzard conditions) is occurring or imminent. Avoid travel; if you must drive, carry an emergency kit (blankets, food, water, flashlight, charged phone). Heating-source safety is critical: never run generators or grills indoors, and check carbon-monoxide detectors before relying on alternative heat sources.
Weather rarely respects county lines — check active alerts in St. Clair County's neighbors:
Subscribe to push or email notifications for new National Weather Service watches and warnings issued for St. Clair County. We'll alert you within seconds of NWS Detroit/Pontiac issuing any severe weather warning for SAME code MIC147.