297
FZUS63 KMQT 230201
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
1001 PM EDT Fri Aug 22 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...

29.7 inch low pressure near James Bay deepens to 29.5 inches
Saturday, which maintains troughing of around 29.7-29.8 inches over
Lake Superior the rest of tonight through Saturday. The parent low
then slowly weakens 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 Monday and Tuesday. High pressure of 30.2 inches
remains over the Lower Midwest Wednesday, though a 29.9 inch trough
is projected to pass over Lake Superior in association with a 29.7
inch shortwave racing through far northern Ontario.


LSZ162-230800-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
1001 PM EDT Fri Aug 22 2025 /901 PM CDT Fri Aug 22 2025/

.REST OF TONIGHT...Southwest winds 10 to 20 knots veering west
after midnight, then increasing to 15 to 25 knots late. Isolated
showers and thunderstorms by midnight. Waves calm to 2 feet
building to 3 to 5 feet occasionally to 7 feet.
.SATURDAY...West winds 20 to 30 knots diminishing to 15 to
25 knots late. Waves subsiding to 2 to 4 feet.
.SATURDAY NIGHT...West winds 20 to 30 knots veering northwest
late. A slight chance of showers after midnight. Waves 2 to
4 feet.
.SUNDAY...Northwest winds 20 to 30 knots. A slight 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. Waves subsiding to calm
to 2 feet.
.MONDAY NIGHT...Northwest winds 10 to 20 knots diminishing to
5 to 15 knots after midnight. Waves calm to 2 feet.
.TUESDAY...Southwest winds 10 to 20 knots veering west. Waves
calm to 2 feet.
.WEDNESDAY...Southwest winds 10 to 20 knots. Waves building to
1 to 3 feet, then subsiding to calm to 2 feet.

$$

LSZ263-230800-
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 Fri Aug 22 2025

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

$$

LSZ264-230800-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
1001 PM EDT Fri Aug 22 2025

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

$$

LSZ265-230800-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
1001 PM EDT Fri Aug 22 2025

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

$$

LSZ266-230800-
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 Fri Aug 22 2025

.REST OF TONIGHT...Southwest winds 10 to 20 knots. Scattered
showers and isolated thunderstorms. Waves calm to 2 feet building
to 1 to 3 feet.
.SATURDAY...West winds 15 to 25 knots increasing to 20 to
30 knots in the afternoon. Waves building to 3 to 6 feet
occasionally to 8 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots. A chance of showers.
A slight chance of thunderstorms after midnight. Waves subsiding
to 2 to 4 feet.
.SUNDAY...Northwest winds 15 to 25 knots increasing to 20 to
30 knots by mid afternoon. A chance of showers and a slight
chance of thunderstorms. 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,
then subsiding to 3 to 6 feet occasionally to 8 feet.
.MONDAY...Northwest winds 20 to 30 knots. Waves building to 4 to
8 feet occasionally to 10 feet.
.MONDAY NIGHT...North winds 15 to 25 knots backing northwest
after midnight. Waves subsiding to 2 to 4 feet.
.TUESDAY...Northwest winds 10 to 20 knots backing west. Waves
subsiding to calm to 2 feet.
.WEDNESDAY...West winds 10 to 20 knots diminishing to 5 to
15 knots. Waves building to 1 to 3 feet.

$$

LSZ267-230800-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
1001 PM EDT Fri Aug 22 2025

.REST OF TONIGHT...Southwest winds 10 to 20 knots. Numerous
showers by midnight. Scattered thunderstorms. Scattered showers
after midnight. Waves calm to 2 feet.
.SATURDAY...West winds 10 to 20 knots increasing to 15 to
25 knots in the afternoon. A slight chance of showers and
thunderstorms through early afternoon. Waves building 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...West winds 15 to 25 knots increasing to 20 to 30 knots
by mid afternoon. A chance of showers and a slight chance of
thunderstorms. Waves subsiding to 2 to 4 feet, then 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,
then subsiding to 3 to 6 feet occasionally to 8 feet.
.MONDAY...Northwest winds 20 to 30 knots. Waves building to 4 to
8 feet occasionally to 10 feet.
.MONDAY NIGHT...North winds 15 to 25 knots backing northwest
after midnight. Waves subsiding to 2 to 4 feet.
.TUESDAY...Northwest winds 10 to 20 knots backing west. Waves
subsiding to 1 to 3 feet.
.WEDNESDAY...West winds 10 to 20 knots. Waves subsiding to calm
to 2 feet.

$$

LSZ261-230800-
MAFOR 2303/
Superior West 11620 15630 11730. Waves 2 to 4 feet overnight.
Waves 3 to 5 feet Saturday. Waves 2 to 4 feet Saturday evening.

Superior North Central 11510 11520 11620 12630 12640 11630. Waves
1 to 3 feet overnight. Waves 2 to 4 feet building to 3 to 5 feet
Saturday. Waves 3 to 5 feet Saturday evening.

Superior South Central 12510 13630 12640 11630. Waves 2 feet or
less overnight. Waves 2 to 4 feet building to 3 to 5 feet
Saturday. Waves 3 to 5 feet Saturday evening.

Superior East 11500 19509 12510 11620 12630 11620 11630. Waves 1
to 2 feet overnight. Waves 1 to 3 feet building to 3 to 6 feet
Saturday. Waves 3 to 6 feet Saturday evening.

$$

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