890
FZUS63 KMKX 212014
GLFLM

OPEN LAKE FORECAST for Lake Michigan
National Weather Service Milwaukee/Sullivan WI
313 PM CDT Fri Aug 21 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...

South to southwest winds will increase today as a low pressure
trough of 29.8 inches approaches southern Wisconsin from the
Minnesota Arrowhead. Ongoing thunderstorms over the far southern
open waters will vacate this afternoon, with more storm development
possible into this evening. A few storms could be strong with
gusty winds, and hail. The aforementioned trough will cross Lake
Michigan from north to south tonight and bring a wind shift to
the northwest. Then look for gusty northerly winds to develop
along a cold front that will track from north to south down Lake
Michigan Saturday evening. A few thunderstorms are possible
along this front. Northerly winds will persist through Sunday as
low pressure around 29.6 inches tracks from Lower Michigan to
Ontario. Variable winds are expected for Monday and Tuesday as
high pressure of 30.1 inches crosses the Upper Great Lakes.

LMZ261-362-364-366-563-565-567-868-220300-
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 PM CDT Fri Aug 21 2026

SHEBOYGAN WI TO PENTWATER MI NORTH...

.TONIGHT...South winds 10 to 20 kt veering to north. Chance of
showers and thunderstorms this evening, then chance of showers
and slight chance of thunderstorms overnight. Waves 3 to 5 ft
subsiding to 1 to 3 ft.
.SATURDAY...North winds 10 to 20 kt becoming northwest to 30 kt.
Chance of showers and thunderstorms in the afternoon. Waves 3 to
5 ft.
.SATURDAY NIGHT...North winds to 30 kt becoming northwest 15 to
25 kt. Waves 4 to 6 ft occasionally to 8 ft.
.SUNDAY...North winds to 30 kt. Waves 4 to 6 ft occasionally to
8 ft.
.SUNDAY NIGHT...North winds to 30 kt diminishing to 10 to 20 kt
overnight. Waves 3 to 5 ft subsiding to 1 to 3 ft.
.MONDAY...Northwest winds 10 to 20 kt. Waves 1 to 2 ft.
.MONDAY NIGHT...Southwest winds 10 to 20 kt diminishing to 5 to
10 kt. Waves 1 to 2 ft.
.TUESDAY...Southwest winds 10 to 20 kt increasing to 15 to 25 kt.
Waves 1 to 3 ft building to 2 to 4 ft.
.WEDNESDAY...Southwest winds 15 to 25 kt increasing to 30 kt.
Chance of showers. Waves 3 to 5 ft.

$$

LMZ080-669-671-673-675-870-872-874-876-878-220300-
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 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 PM CDT Fri Aug 21 2026

SHEBOYGAN WI TO PENTWATER MI SOUTH TO WINTHROP HARBOR IL TO SOUTH
HAVEN MI...

.TONIGHT...South winds 10 to 20 kt veering to northwest. Chance
of showers and thunderstorms this evening, then chance of showers
and slight chance of thunderstorms overnight. Waves 3 to 5 ft
subsiding to 2 to 4 ft.
.SATURDAY...Northwest winds 10 to 20 kt becoming north 15 to
25 kt. Slight chance of showers and thunderstorms in the
afternoon. Waves 4 to 6 ft occasionally to 8 ft.
.SATURDAY NIGHT...North winds 15 to 25 kt. Waves 4 to 6 ft
occasionally to 8 ft.
.SUNDAY...North winds to 30 kt. Waves 5 to 8 ft occasionally to
10 ft.
.SUNDAY NIGHT...North winds 15 to 25 kt becoming northwest 10 to
15 kt overnight. Waves 4 to 6 ft occasionally to 8 ft subsiding
to 2 to 4 ft.
.MONDAY...North winds 10 to 15 kt. Waves 1 to 2 ft.
.MONDAY NIGHT...East winds 5 to 10 kt veering to south. Waves
1 to 2 ft.
.TUESDAY...South winds 10 to 20 kt increasing to 15 to 25 kt.
Waves 1 to 3 ft building to 2 to 4 ft.
.WEDNESDAY...Southwest winds 15 to 25 kt. Waves 3 to 5 ft.

$$

LMZ777-779-220300-
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-
313 PM CDT Fri Aug 21 2026

WINTHROP HARBOR IL TO SOUTH HAVEN MI SOUTH...

...SEVERE THUNDERSTORM WATCH 610 IN EFFECT UNTIL 10 PM CDT THIS
EVENING...

.TONIGHT...South winds 10 to 20 kt veering to northwest. Chance
of showers and thunderstorms this evening, then chance of showers
and slight chance of thunderstorms overnight. Waves 3 to 5 ft
subsiding to 2 to 4 ft.
.SATURDAY...Northwest winds 10 to 20 kt becoming north 15 to
25 kt. Slight chance of showers and thunderstorms in the
afternoon. Waves 4 to 6 ft occasionally to 8 ft.
.SATURDAY NIGHT...North winds 15 to 25 kt. Waves 4 to 6 ft
occasionally to 8 ft.
.SUNDAY...North winds to 30 kt. Waves 5 to 8 ft occasionally to
10 ft.
.SUNDAY NIGHT...North winds 15 to 25 kt becoming northwest 10 to
15 kt overnight. Waves 4 to 6 ft occasionally to 8 ft subsiding
to 2 to 4 ft.
.MONDAY...North winds 10 to 15 kt. Waves 1 to 2 ft.
.MONDAY NIGHT...East winds 5 to 10 kt veering to south. Waves
1 to 2 ft.
.TUESDAY...South winds 10 to 20 kt increasing to 15 to 25 kt.
Waves 1 to 3 ft building to 2 to 4 ft.
.WEDNESDAY...Southwest winds 15 to 25 kt. Waves 3 to 5 ft.

$$
LMZ761-220300-
MAFOR 2122 AMD/
MICHIGAN NORTH 11420 11520 11610 11720 11820 12720 11730. A
chance of showers and thunderstorms this evening, then a chance
of showers overnight. A chance of showers and thunderstorms
Saturday afternoon. Waves 2 to 4 feet subsiding to 1 to 3 feet
tonight. Waves 1 to 3 feet Saturday.

MICHIGAN SOUTH...SEVERE THUNDERSTORM WATCH IN EFFECT...11420
11410 11510 11620 13720 11830. 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 tonight. Waves 2 to 4 feet building to 3 to 5 feet
Saturday.

$$


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