Special Marine Warning for Lake Michigan from Sheboygan WI to Winthrop Harbor IL
This alert is no longer in effect.
NOAA issued it on August 18, 2026, 5 days ago. Warnings of this kind stay in effect for hours to a few days, so this page is a historical record of what was issued, not a current warning. For conditions where you are right now, check weather.gov (US), weather.gc.ca (Canada), the Met Office (UK), or the Bureau of Meteorology (Australia).
Areazine synthesizes this NWS weather alert directly from NOAA's official public data feed. See our methodology for full source attribution and refresh cadence.
NWS Milwaukee/Sullivan WI issued a Special Marine Warning for Lake Michigan nearshore and open waters until 8:30 PM CDT due to severe thunderstorms with wind gusts over 50 knots and small hail.
Read this weather record in 30 seconds
- Record type
- Special Marine Warning
- Affected area
- Lake Michigan from Sheboygan WI to Winthrop Harbor IL
- Issued
- August 18, 2026
- Issuing authority
- NWS Milwaukee/Sullivan WI
Marine notices apply to named waters or shoreline zones. They may not describe conditions on land, even when the nearest place name is the same.
Record status: historical. It was issued 5 days ago; use the issuing agency's live warning service for current conditions in Lake Michigan from Sheboygan WI to Winthrop Harbor IL.
Alert Details
Special Marine Warning issued by NWS Milwaukee/Sullivan WI (NOAA). Effective from August 18 at 6:28 PM CDT until August 18 at 8:30 PM CDT. Severity: Severe. Urgency: Immediate. Certainty: Likely.
Affected Areas
Lake Michigan nearshore and open waters to mid lake from Sheboygan WI to Winthrop Harbor IL, including zones LMZ643, LMZ644, LMZ645, LMZ646, LMZ669, LMZ671, LMZ673, and LMZ675.
What You Should Do
Boats could suffer significant structural damage in high winds. Small craft could capsize in suddenly higher waves. Avoid the area.
Expected Conditions
Severe thunderstorms located along a line extending from 11 nm west of Port Washington to 23 nm west of Milwaukee to 50 nm northwest of McHenry, moving southeast at 30 knots. Hazard includes wind gusts in excess of 50 knots and small hail.
Timeline
Alert effective August 18 at 6:28 PM CDT and expires August 18 at 8:30 PM CDT. Severe thunderstorms will remain over mainly open waters.
Original source: NOAA Official Notice ↗
Related Weather Alerts
All Weather Alerts →Nationwide notices with similar length or severity timing 8
Two Areazine-derived peer sets for this NWS weather alert: nearest notices by body length and by same severity near the same agency date. Peers come from other categories so they are not the same-feed Related list above.
Similar body length
Nearest notices by article body length (977 characters here).
Similar severity timing
Same severity (high) notices issued closest in time to August 18, 2026.
Frequently Asked Questions
Common questions about this NWS weather alert.