609
FZUS63 KMKX 180813
GLFLM

OPEN LAKE FORECAST for Lake Michigan
National Weather Service Milwaukee/Sullivan WI
313 AM CDT Tue Aug 18 2026

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...

Low pressure around 29.6 inches moving across the Hudson Bay
region today will drag a cold front southward across Lake Michigan
this afternoon and evening. Expect prevailing west to
southwesterly winds ahead of the cold front along with a few
thunderstorms through this evening. Then the cold front will push
down the Lake by Wednesday bringing a north-northwesterly winds
shift. Winds will weaken and become more variable as high pressure
around 30.0 inches tracks through the western Great Lakes through
Thursday. Southwesterly winds and thunderstorm chances return
later Friday as another system is progged to bring another cold
front across the Upper Great Lakes region.

LMZ261-362-364-366-563-565-567-868-181515-
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-
313 AM CDT Tue Aug 18 2026

SHEBOYGAN WI TO PENTWATER MI NORTH...

.TODAY...West winds 10 to 20 kt becoming southwest 15 to 25 kt.
Slight chance of showers and thunderstorms this morning, then
chance of showers and thunderstorms this afternoon. Waves 2 to
4 ft.
.TONIGHT...Northwest winds 10 to 20 kt diminishing to 10 to
15 kt. Chance of showers and thunderstorms in the evening. Waves
2 to 4 ft subsiding to 1 to 3 ft.
.WEDNESDAY...Northwest winds 10 to 15 kt backing to southwest
10 to 20 kt. Waves 1 to 2 ft.
.WEDNESDAY NIGHT...South winds 10 to 15 kt becoming southeast.
Waves 1 to 2 ft.
.THURSDAY...Southwest winds 10 to 15 kt increasing to 10 to
20 kt. Waves 1 to 2 ft.
.THURSDAY NIGHT...South winds 10 to 20 kt increasing to 15 to
25 kt. Waves 2 to 4 ft.
.FRIDAY...Southwest winds to 30 kt. Chance of showers. Waves 3 to
5 ft.
.SATURDAY...Northwest winds 10 to 20 kt increasing to 30 kt.
Waves 1 to 3 ft.

$$

LMZ080-669-671-673-675-777-779-870-872-874-876-878-181515-
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-
313 AM CDT Tue Aug 18 2026

SHEBOYGAN WI TO PENTWATER MI SOUTH...

.TODAY...West winds 10 to 20 kt becoming southwest 15 to 25 kt.
Chance of showers and slight chance of thunderstorms this
afternoon. Waves 2 to 4 ft.
.TONIGHT...Southwest winds 10 to 20 kt veering to north 10 to
15 kt. Chance of showers and thunderstorms in the evening, then
slight chance of showers and thunderstorms overnight. Waves 3 to
5 ft subsiding to 1 to 3 ft.
.WEDNESDAY...North winds 10 to 15 kt increasing to 10 to 20 kt.
Waves 1 to 3 ft.
.WEDNESDAY NIGHT...Northeast winds 10 to 15 kt becoming southeast
5 to 10 kt. Waves 1 to 2 ft.
.THURSDAY...Southeast winds 5 to 10 kt becoming south 10 to 20 kt
in the afternoon. Waves 1 to 2 ft.
.THURSDAY NIGHT...South winds 10 to 20 kt. Waves 1 to 3 ft.
.FRIDAY...Southwest winds 10 to 20 kt increasing to 15 to 25 kt.
Waves 2 to 4 ft.
.SATURDAY...Northwest winds 10 to 20 kt increasing to 15 to
25 kt. Waves 2 to 4 ft.

$$

LMZ761-181515-
MAFOR 1810/
MICHIGAN NORTH 11520 11620 12530 11630 13810. A chance of showers
and thunderstorms this afternoon and evening. Waves 1 to 3 feet
building to 2 to 4 feet today. Waves 2 to 4 feet subsiding to 1
to 3 feet tonight.

MICHIGAN SOUTH 11620 12520 12530 11620 11710 11810. A chance of
showers this afternoon. A chance of showers and thunderstorms
this evening. Waves 1 to 3 feet building to 2 to 4 feet today.
Waves 2 to 4 feet subsiding to 1 to 3 feet tonight.

$$


Wagner

Experimental modernized open lake forecast is available online at
weather.gov/mkx/glftable

Graphical marine forecasts are available online at:
weather.gov/greatlakes