297
FZUS63 KMKX 181724
GLFLM

OPEN LAKE FORECAST for Lake Michigan
National Weather Service Milwaukee/Sullivan WI
1223 PM CDT Mon Aug 18 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...

High pressure around 30.4 inches sets up across Ontario/Quebec
today. Meanwhile a weak area of low pressure over South Dakota
will move into southern Minnesota overnight and gradually drag a
cold front southeast across the region, clearing the south end of
Lake Michigan by midday Tuesday. This front will bring multiple
rounds of showers and storms from this evening through Monday
night. Winds will shift northeast to southeast this morning.
After the front exits the area, winds will shift to the north
from Tuesday through Friday.

LMZ261-362-364-366-563-565-567-868-190300-
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-
1223 PM CDT Mon Aug 18 2025

SHEBOYGAN WI TO PENTWATER MI NORTH...

.TONIGHT...Southeast winds 10 to 20 kt becoming south. Chance of
showers and thunderstorms. Waves 4 to 6 ft occasionally to 8 ft
subsiding to 3 to 5 ft.
.TUESDAY...South winds 10 to 20 kt backing to north. Slight
chance of showers and thunderstorms in the morning, then slight
chance of showers in the afternoon. Waves 2 to 4 ft subsiding to
1 to 3 ft.
.TUESDAY NIGHT...North winds 10 to 20 kt. Waves 3 to 5 ft.
.WEDNESDAY...North winds 10 to 20 kt increasing to 15 to 25 kt.
Waves 3 to 5 ft.
.WEDNESDAY NIGHT...Northeast winds 15 to 25 kt diminishing to
10 to 20 kt. Waves 3 to 5 ft subsiding to 2 to 4 ft.
.THURSDAY...Northeast winds 5 to 10 kt increasing to 10 to 15 kt.
Waves 1 to 2 ft.
.THURSDAY NIGHT...East winds 10 to 15 kt veering to south. Waves
1 to 2 ft.
.FRIDAY...Southwest winds 10 to 20 kt. Waves 1 to 3 ft.
.SATURDAY...West winds 10 to 20 kt. Waves 1 to 3 ft.

$$

LMZ669-671-673-675-777-779-190300-
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-
1223 PM CDT Mon Aug 18 2025

SHEBOYGAN WI TO PENTWATER MI SOUTH...

...SEVERE THUNDERSTORM WATCH 599 IN EFFECT UNTIL 6 PM CDT THIS
EVENING...

.TONIGHT...Southeast winds 10 to 20 kt becoming south. Showers
likely with a chance of thunderstorms. Waves 4 to 6 ft
occasionally to 8 ft subsiding to 3 to 5 ft.
.TUESDAY...Southwest winds 10 to 20 kt veering to north 10 to
15 kt. Chance of showers and slight chance of thunderstorms in
the morning, then slight chance of showers and thunderstorms in
the afternoon. Waves 2 to 4 ft subsiding to 1 to 3 ft.
.TUESDAY NIGHT...North winds 10 to 15 kt increasing to 10 to
20 kt. Waves 2 to 4 ft building to 4 to 6 ft occasionally to
8 ft.
.WEDNESDAY...North winds 15 to 25 kt. Waves 5 to 8 ft
occasionally to 10 ft.
.WEDNESDAY NIGHT...North winds 15 to 25 kt becoming northeast
10 to 20 kt. Waves 5 to 8 ft occasionally to 10 ft subsiding to
4 to 7 ft occasionally to 9 ft.
.THURSDAY...Northeast winds 10 to 15 kt increasing to 10 to
20 kt. Waves 3 to 5 ft subsiding to 1 to 3 ft.
.THURSDAY NIGHT...North winds 10 to 15 kt becoming east 5 to
10 kt. Waves 1 to 2 ft.
.FRIDAY...Southwest winds 5 to 10 kt becoming south 10 to 15 kt.
Waves 1 to 2 ft.
.SATURDAY...Northwest winds 10 to 15 kt becoming west. Waves 1 to
3 ft.

$$

LMZ080-870-872-874-876-878-190300-
Lake Michigan from Michigan City IN to St. Joseph MI 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-
1223 PM CDT Mon Aug 18 2025

WILMETTE HARBOR IL TO ST. JOSEPH MI SOUTH TO ROCK ISLAND PASSAGE
TO CHARLEVOIX MI...

.TONIGHT...Southeast winds 10 to 20 kt becoming south. Chance of
showers and thunderstorms. Waves 3 to 5 ft.
.TUESDAY...Southwest winds 10 to 20 kt veering to northwest 10 to
15 kt. Chance of showers and slight chance of thunderstorms in
the morning, then slight chance of showers and thunderstorms in
the afternoon. Waves 2 to 4 ft subsiding to 1 to 3 ft.
.TUESDAY NIGHT...North winds 10 to 15 kt increasing to 10 to
20 kt. Waves 2 to 4 ft building to 4 to 6 ft occasionally to
8 ft.
.WEDNESDAY...North winds 10 to 20 kt increasing to 15 to 25 kt.
Waves 4 to 7 ft occasionally to 9 ft.
.WEDNESDAY NIGHT...North winds 15 to 25 kt becoming northeast
10 to 20 kt. Waves 5 to 8 ft occasionally to 10 ft subsiding to
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 2 ft.
.THURSDAY NIGHT...North winds 10 to 20 kt veering to east 5 to
10 kt. Waves 1 to 3 ft.
.FRIDAY...South winds 10 to 15 kt becoming southwest. Waves 1 to
2 ft.
.SATURDAY...Northwest winds 10 to 20 kt becoming west. Waves 2 to
4 ft.

$$
LMZ761-190300-
MAFOR 1822 AMD/
MICHIGAN NORTH 13330 11320 11420 11320 11110 11810. A chance of
showers early this evening, then a chance of showers and
thunderstorms this evening. A chance of showers overnight. Waves
2 to 4 feet subsiding to 1 to 3 feet.

MICHIGAN SOUTH...SEVERE THUNDERSTORM WATCH IN EFFECT...11320
11310 12420 11520 11610 11710 11810. A chance of showers and
thunderstorms tonight. A chance of showers Tuesday morning. Waves
2 to 4 feet subsiding to 1 to 3 feet, then building to 2 to 4
feet tonight. Waves 2 to 4 feet subsiding to 1 to 3 feet Tuesday.

$$


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