FZUS63 KMKX 191401 GLFLM OPEN LAKE FORECAST for Lake Michigan National Weather Service Milwaukee/Sullivan WI Issued by National Weather Service Green Bay WI 901 AM CDT Tue Aug 19 2025 FOR WATERS BEYOND FIVE NAUTICAL MILES OF SHORE ON Lake Michigan. Waves are provided as a range of significant wave heights, which is the average of the highest 1/3 of the wave, along with the average height of the highest 10% of the waves which will occasionally be encountered. .SYNOPSIS... Weak low pressure around 29.9 inches will cross southern Lower Michigan today. High pressure around 30.1 inches sitting over Ontario will remain in place through much of the week. A period of elevated northerly winds is expected today, then light and variable winds will develop as the high pressure strengthens to 30.2 inches as it glides over Lake Michigan later in the week. LMZ261-362-364-366-563-565-567-868-192130- Lake Michigan from Seul Choix Point to Rock Island Passage 5 NM offshore to Mid Lake- Lake Michigan South of a line from Seul Choix Point to the Mackinac Bridge and north of a line from Charlevoix MI to South Fox Island 5 NM offshore- Lake Michigan from Charlevoix to Point Betsie MI 5 NM offshore to Mid Lake- Lake Michigan from Point Betsie to Manistee MI 5 NM offshore to Mid Lake- Lake Michigan from Rock Island Passage to Sturgeon Bay WI- Lake Michigan from Sturgeon Bay to Two Rivers WI 5 NM offshore to Mid Lake- Lake Michigan from Two Rivers to Sheboygan WI 5 NM offshore to Mid Lake- Lake Michigan from Pentwater to Manistee MI 5 NM offshore to Mid Lake- 901 AM CDT Tue Aug 19 2025 SHEBOYGAN WI TO PENTWATER MI NORTH... .REST OF TODAY...Northeast winds 10 to 20 kt. Waves 2 to 4 ft. .TONIGHT...Northeast winds 10 to 20 kt diminishing to 10 to 15 kt. Patchy fog overnight. Slight chance of showers overnight. Waves 1 to 3 ft. .WEDNESDAY...Northeast winds 10 to 20 kt becoming north 15 to 25 kt. Chance of showers in the morning. Waves 1 to 3 ft building to 3 to 5 ft. .WEDNESDAY NIGHT...Northeast winds 15 to 25 kt diminishing to 10 to 15 kt overnight. Waves 3 to 5 ft subsiding to 2 to 4 ft. .THURSDAY...Northeast winds 5 to 10 kt becoming north 10 to 15 kt. Waves 1 to 2 ft. .THURSDAY NIGHT...East winds 10 to 15 kt veering to south 5 to 10 kt. Waves 1 to 2 ft. .FRIDAY...Southwest winds 10 to 20 kt. Waves 1 to 2 ft. .SATURDAY...West winds 10 to 20 kt increasing to 15 to 25 kt. Waves 1 to 3 ft. $$ LMZ080-669-671-673-675-777-779-870-872-874-876-878-192130- Lake Michigan from Michigan City IN to St. Joseph MI 5 NM offshore to Mid Lake- Lake Michigan from Sheboygan to Port Washington WI 5 NM offshore to Mid Lake- Lake Michigan from Port Washington to North Point Light WI 5 NM offshore to Mid Lake- Lake Michigan from North Point Light to Wind Point WI 5 NM offshore to Mid Lake- Lake Michigan from Wind Point WI to Winthrop Harbor IL 5 NM offshore to Mid Lake- Lake Michigan from Winthrop Harbor to Wilmette Harbor IL 5 NM offshore to Mid Lake- Lake Michigan from Wilmette Harbor IL to Michigan City IN 5 NM offshore to Mid Lake- Lake Michigan from Whitehall to Pentwater MI 5 NM offshore to Mid Lake- Lake Michigan from Grand Haven to Whitehall MI 5 NM offshore to Mid Lake- Lake Michigan from Holland to Grand Haven MI 5 NM offshore to Mid Lake- Lake Michigan from South Haven to Holland MI 5 NM offshore to Mid Lake- Lake Michigan from St. Joseph to South Haven MI 5 NM offshore to Mid Lake- 901 AM CDT Tue Aug 19 2025 SHEBOYGAN WI TO PENTWATER MI SOUTH... .REST OF TODAY...Northwest winds 10 to 20 kt becoming north. Isolated showers through mid morning. Waves 3 to 5 ft. .TONIGHT...North winds 10 to 20 kt. Slight chance of showers overnight. Waves 3 to 5 ft. .WEDNESDAY...Northeast winds 10 to 20 kt becoming north 15 to 25 kt. Waves 3 to 5 ft. .WEDNESDAY NIGHT...North winds 15 to 25 kt becoming east 10 to 20 kt. Waves 4 to 6 ft occasionally to 8 ft. .THURSDAY...Northeast winds 10 to 15 kt becoming north 10 to 20 kt. Waves 2 to 4 ft subsiding to 1 to 3 ft. .THURSDAY NIGHT...Northeast winds 10 to 20 kt becoming east 5 to 10 kt. Waves 1 to 3 ft. .FRIDAY...South winds 5 to 10 kt increasing to 10 to 15 kt. Waves 1 to 2 ft. .SATURDAY...Northwest winds 10 to 20 kt becoming west. Waves 2 to 4 ft. $$ LMZ761-192130- MAFOR 1916/ MICHIGAN NORTH 11120 11110 12120 12110 11120 11110. A chance of showers Wednesday morning. Waves 1 to 3 feet. MICHIGAN SOUTH 15820 11820 11120. Waves 2 to 4 feet. $$ WFO MKX Experimental modernized open lake forecast is available online at weather.gov/mkx/glftable Graphical marine forecasts are available online at: weather.gov/greatlakes