628
FZUS63 KMQT 220201
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
1001 PM EDT Thu Aug 21 2025

For waters beyond 5 nautical miles of shore on Lake Superior.

Waves are the significant wave height - the average of the
highest 1/3 of the wave spectrum. Occasional wave height is the
average of the highest 1/10 of the wave spectrum.

.SYNOPSIS...

A high pressure of 30.1 inches remains over the lake tonight. By
Friday morning, the high shifts to the southern portions of the
Great Lakes basin thanks to a 29.7 inch low over northern Manitoba
to the northwest and Hurricane Erin at 28.3 inches over the Gulf
Stream east of New Jersey. As Erin shifts north and east through the
day Friday, the high is allowed to shift over the East Coast while
the 29.7 inch low from northern Manitoba slides into northern
Ontario. This low deepens to 29.5 inches and lifts toward James Bay
Saturday before slowly weakening to 29.6 inches Sunday and Monday as
it moves into northern Quebec. As this happens, 30.2 inch high
pressure stretches over the Great Plains early next week, eventually
bringing ridging of at least 30.1 inches back over the western
portions of Lake Superior on Tuesday.


LSZ162-220800-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
1001 PM EDT Thu Aug 21 2025 /901 PM CDT Thu Aug 21 2025/

.REST OF TONIGHT...Southeast winds 5 to 15 knots veering west
after midnight, then backing southwest late. A chance of showers
and thunderstorms. Waves calm to 2 feet.
.FRIDAY...West winds 10 to 20 knots backing southwest late. A
chance of showers and a slight chance of thunderstorms. Waves
calm to 2 feet.
.FRIDAY NIGHT...Southwest winds 10 to 20 knots becoming west
15 to 25 knots after midnight. Waves building to 2 to 4 feet.
.SATURDAY...West winds 20 to 30 knots. A slight chance of showers
by mid afternoon. Waves building to 3 to 5 feet occasionally to
7 feet, then subsiding to 2 to 4 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots increasing to 20 to
30 knots after midnight. A slight chance of showers after
midnight. Waves 2 to 4 feet.
.SUNDAY...Northwest winds 20 to 30 knots. A chance of showers.
Waves building to 3 to 5 feet occasionally to 7 feet, then
subsiding to 2 to 4 feet.
.SUNDAY NIGHT...Northwest winds 15 to 25 knots. Waves 2 to
4 feet.
.MONDAY...Northwest winds 10 to 20 knots becoming north 5 to
15 knots. Waves subsiding to calm to 2 feet.
.TUESDAY...Southwest winds 5 to 15 knots veering west. Waves calm
to 2 feet.

$$

LSZ263-220800-
Lake Superior from Saxon Harbor WI to Upper Entrance to Portage
Canal MI 5NM off shore to the US/Canadian border including Isle
Royale National Park-
1001 PM EDT Thu Aug 21 2025

.REST OF TONIGHT...Southeast winds 5 to 15 knots veering south
after midnight, then becoming southwest 10 to 20 knots late. A
slight chance of showers and thunderstorms. Waves calm to 2 feet.
.FRIDAY...West winds 10 to 20 knots backing southwest late. A
chance of showers and a slight chance of thunderstorms. Waves
building to 1 to 3 feet, then subsiding to calm to 2 feet.
.FRIDAY NIGHT...Southwest winds 10 to 20 knots veering west after
midnight, then increasing to 15 to 25 knots late. Waves building
to 3 to 5 feet occasionally to 7 feet.
.SATURDAY...West winds 15 to 25 knots increasing to 20 to
30 knots by mid afternoon. A slight chance of showers by mid
afternoon. Waves building to 4 to 7 feet occasionally to 9 feet.
.SATURDAY NIGHT...West winds 20 to 30 knots diminishing to 15 to
25 knots after midnight. A chance of showers. Waves subsiding to
3 to 6 feet occasionally to 8 feet.
.SUNDAY...Northwest winds 15 to 25 knots. A chance of showers.
Waves subsiding to 3 to 5 feet occasionally to 7 feet.
.SUNDAY NIGHT...Northwest winds 15 to 25 knots. A chance of
showers. Waves building to 3 to 6 feet occasionally to 8 feet.
.MONDAY...North winds 15 to 25 knots diminishing to 10 to
20 knots. Waves subsiding to calm to 2 feet.
.TUESDAY...North winds 5 to 15 knots backing west. Waves calm to
2 feet.

$$

LSZ264-220800-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
1001 PM EDT Thu Aug 21 2025

.REST OF TONIGHT...South winds 5 to 15 knots becoming southwest
10 to 20 knots late. A slight chance of showers and
thunderstorms. Waves calm to 2 feet.
.FRIDAY...West winds 10 to 20 knots diminishing to 5 to 15 knots
in the afternoon, then backing southwest late. Patchy fog by mid
afternoon. A chance of showers and a slight chance of
thunderstorms by mid afternoon. Waves building to 1 to 3 feet,
then subsiding to calm to 2 feet.
.FRIDAY NIGHT...Southwest winds 5 to 15 knots increasing to 10 to
20 knots after midnight, then becoming west 15 to 25 knots late.
A slight chance of showers through midnight. Waves building to
2 to 4 feet.
.SATURDAY...West winds 15 to 25 knots increasing to 20 to
30 knots by mid afternoon. Waves building to 4 to 7 feet
occasionally to 9 feet, then subsiding to 3 to 6 feet
occasionally to 8 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots. A slight chance of
showers after midnight. Waves subsiding to 3 to 5 feet
occasionally to 7 feet.
.SUNDAY...Northwest winds 15 to 25 knots. A chance of showers.
Waves building to 3 to 6 feet occasionally to 8 feet.
.SUNDAY NIGHT...Northwest winds 15 to 25 knots. A chance of
showers. Waves building to 3 to 6 feet occasionally to 8 feet.
.MONDAY...North winds 15 to 25 knots diminishing to 10 to
20 knots. Waves subsiding to calm to 2 feet.
.TUESDAY...Northwest winds 5 to 15 knots backing west. Waves calm
to 2 feet.

$$

LSZ265-220800-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
1001 PM EDT Thu Aug 21 2025

.REST OF TONIGHT...Southeast winds 10 to 20 knots becoming south
5 to 15 knots after midnight, then becoming southwest 10 to
20 knots late. Waves calm to 2 feet.
.FRIDAY...Southwest winds 10 to 20 knots veering west in the
afternoon. A chance of showers and thunderstorms by mid
afternoon. Waves calm to 2 feet.
.FRIDAY NIGHT...Southwest winds 10 to 20 knots becoming west
15 to 25 knots late. A slight chance of showers and thunderstorms
through midnight. Waves building to 1 to 3 feet.
.SATURDAY...West winds 20 to 30 knots. Waves building to 3 to
5 feet occasionally to 7 feet.
.SATURDAY NIGHT...West winds 20 to 30 knots diminishing to 15 to
25 knots after midnight. A chance of showers after midnight.
Waves subsiding to 2 to 4 feet.
.SUNDAY...West winds 15 to 25 knots becoming northwest 20 to
30 knots by mid afternoon. A chance of showers. Waves 2 to
4 feet.
.SUNDAY NIGHT...Northwest winds 20 to 30 knots. A chance of
showers. Waves building to 3 to 5 feet occasionally to 7 feet.
.MONDAY...Northwest winds 20 to 30 knots becoming north 10 to
20 knots. Waves building to 3 to 6 feet occasionally to 8 feet,
then subsiding to 1 to 3 feet.
.TUESDAY...Northwest winds 10 to 20 knots backing west. Waves
subsiding to calm to 2 feet.

$$

LSZ266-220800-
Lake Superior East of a line from Manitou Island to Marquette MI
and West of a line from Grand Marais MI to the US/Canadian Border
Beyond 5NM from shore-
1001 PM EDT Thu Aug 21 2025

.REST OF TONIGHT...Southeast winds 10 to 20 knots veering
southwest late. Patchy fog by midnight. A slight chance of
showers and thunderstorms after midnight. Waves calm to 2 feet.
.FRIDAY...Southwest winds 10 to 20 knots veering west late. A
chance of showers and a slight chance of thunderstorms by mid
afternoon. Waves calm to 2 feet.
.FRIDAY NIGHT...Southwest winds 10 to 20 knots. A chance of
showers and thunderstorms. Waves building to 2 to 4 feet.
.SATURDAY...West winds 15 to 25 knots. Waves building to 3 to
6 feet occasionally to 8 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots. A chance of showers
after midnight. Waves subsiding to 3 to 5 feet occasionally to
7 feet.
.SUNDAY...West winds 15 to 25 knots becoming northwest 20 to
30 knots by mid afternoon. A chance of showers. Waves building to
3 to 6 feet occasionally to 8 feet.
.SUNDAY NIGHT...Northwest winds 20 to 30 knots. A chance of
showers. Waves building to 4 to 7 feet occasionally to 9 feet.
.MONDAY...Northwest winds 20 to 30 knots becoming north 15 to
25 knots. Waves building to 5 to 8 feet occasionally to 10 feet,
then subsiding to 2 to 4 feet.
.TUESDAY...Northwest winds 10 to 20 knots backing west. Waves
subsiding to calm to 2 feet.

$$

LSZ267-220800-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
1001 PM EDT Thu Aug 21 2025

.REST OF TONIGHT...Southeast winds 5 to 15 knots veering south
after midnight, then increasing to 10 to 20 knots late. Patchy
fog by midnight. Waves calm to 2 feet.
.FRIDAY...Southwest winds 10 to 20 knots diminishing to 5 to
15 knots late. A chance of showers and a slight chance of
thunderstorms by mid afternoon. Waves calm to 2 feet.
.FRIDAY NIGHT...Southwest winds 10 to 20 knots. Showers likely
through midnight. A chance of thunderstorms. A chance of showers
after midnight. Waves calm to 2 feet.
.SATURDAY...West winds 15 to 25 knots. A slight chance of showers
through early afternoon. Waves building to 3 to 5 feet
occasionally to 7 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots. A chance of showers
after midnight. Waves 3 to 5 feet occasionally to 7 feet.
.SUNDAY...West winds 15 to 25 knots veering northwest by mid
afternoon. Showers likely through early afternoon, then a chance
of showers by mid afternoon. Waves building to 3 to 6 feet
occasionally to 8 feet.
.SUNDAY NIGHT...Northwest winds 15 to 25 knots increasing to
20 to 30 knots after midnight. A chance of showers. Waves
building to 4 to 7 feet occasionally to 9 feet.
.MONDAY...Northwest winds 20 to 30 knots becoming north 15 to
25 knots. Waves building to 5 to 8 feet occasionally to 10 feet,
then subsiding to 2 to 4 feet.
.TUESDAY...Northwest winds 10 to 20 knots. Waves subsiding to
calm to 2 feet.

$$

LSZ261-220800-
MAFOR 2203/
Superior West 11410 12520 13620 12520. A chance of showers and
thunderstorms overnight. A chance of showers Friday afternoon.
Waves 1 to 3 feet.

Superior North Central 12410 11510 11520 12620 12520. A chance of
showers Friday afternoon. A chance of showers and thunderstorms
Friday evening. Waves 1 to 3 feet.

Superior South Central 11310 13510 12610 11616 11510. A chance of
thunderstorms Friday afternoon and Friday evening. Waves 2 feet
or less.

Superior East 11310 11410 14510 11500 11510. A chance of showers
and thunderstorms Friday evening. Waves 2 feet or less.

$$

WFO MQT

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

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