604
FZUS63 KMKX 182012
GLFLM

OPEN LAKE FORECAST for Lake Michigan
National Weather Service Milwaukee/Sullivan WI
312 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 around 29.9 inches is
tracking across southeastern MN into southern WI. This will bring
additional rounds of showers and storms across southern portions
of Lake Michigan this evening/tonight. As the low pressure and
associated cold front pushes through overnight can expect to see
more stronger northerly winds into Tuesday. High pressure then
settles into the region through midweek with winds shifting.

LMZ261-362-364-366-563-565-567-868-190315-
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-
312 PM CDT Mon Aug 18 2025

SHEBOYGAN WI TO PENTWATER MI NORTH...

.TONIGHT...Southeast winds 15 to 25 kt diminishing to 10 to
20 kt. Chance of showers and thunderstorms this evening, then
chance of showers and slight chance of thunderstorms overnight.
Waves 3 to 5 ft.
.TUESDAY...Southeast winds 10 to 20 kt backing to northeast.
Slight chance of showers in the morning. Waves 2 to 4 ft.
.TUESDAY NIGHT...North winds 10 to 20 kt. Waves 2 to 4 ft.
.WEDNESDAY...North winds 10 to 20 kt increasing to 15 to 25 kt.
Waves 3 to 5 ft.
.WEDNESDAY NIGHT...Northeast winds 10 to 20 kt. Waves 3 to 5 ft
subsiding to 2 to 4 ft.
.THURSDAY...Northeast winds 5 to 10 kt becoming north 10 to 20 kt
in the afternoon. 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...Northwest winds 10 to 20 kt becoming west 15 to
25 kt. Waves 1 to 3 ft.

$$

LMZ671-673-675-777-779-190315-
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-
312 PM CDT Mon Aug 18 2025

PORT WASHINGTON WI TO WHITEHALL MI SOUTH...

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

.TONIGHT...Southeast winds 10 to 20 kt becoming southwest. Chance
of showers and thunderstorms. Waves 3 to 5 ft.
.TUESDAY...West winds 10 to 20 kt veering to north. 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.
.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 4 to 6 ft occasionally to 8 ft.
.WEDNESDAY NIGHT...North winds 15 to 25 kt becoming northeast
10 to 20 kt. Waves 4 to 7 ft occasionally to 9 ft.
.THURSDAY...Northeast winds 10 to 15 kt increasing to 10 to
20 kt. Waves 2 to 4 ft subsiding to 1 to 3 ft.
.THURSDAY NIGHT...North winds 10 to 20 kt becoming northeast 5 to
10 kt. Waves 1 to 3 ft.
.FRIDAY...Southwest winds 5 to 10 kt becoming south. Waves 1 to
2 ft.
.SATURDAY...Northwest winds 10 to 20 kt. Waves 2 to 4 ft.

$$

LMZ080-669-870-872-874-876-878-190315-
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 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-
312 PM CDT Mon Aug 18 2025

SHEBOYGAN WI TO PENTWATER MI SOUTH TO PORT WASHINGTON WI TO
WHITEHALL 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 north. Chance
of showers and slight chance of thunderstorms in the morning.
Waves 3 to 5 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 4 to 6 ft occasionally to 8 ft.
.WEDNESDAY NIGHT...North winds 15 to 25 kt becoming northeast
10 to 20 kt. Waves 4 to 7 ft occasionally to 9 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...Southwest winds 5 to 10 kt increasing to 10 to 15 kt.
Waves 1 to 2 ft.
.SATURDAY...Northwest winds 10 to 20 kt. Waves 2 to 4 ft.

$$

LMZ761-190315-
MAFOR 1822/
MICHIGAN NORTH 12330 11336 12320 11220 11110 11120. A chance of
thunderstorms this evening. Waves 2 to 4 feet subsiding to 1 to 3
feet.

MICHIGAN SOUTH...SEVERE THUNDERSTORM WATCH IN EFFECT...12320
12426 11520 11610 11720 11820. A chance of thunderstorms tonight.
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.

$$


Wagner

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

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