362
FZUS63 KMQT 242002
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
401 PM EDT Sun Aug 24 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...

29.5 inch low pressure over James Bay is sending 29.8 inch troughing
over Lake Superior. The parent low continues to spin near James Bay
through early Monday, then gradually weakens while moving eastward
through Quebec the rest of the day. As this happens, 30.2 inch high
pressure stretches over the Great Plains, with a ridge building to
30.1 inches over the Great Lakes the rest of the day Monday and
lingering over the area Tuesday. High pressure of 30.2 inches
remains over the Lower Midwest Wednesday, though a 29.9 inch trough
is projected to drop south over Lake Superior Wednesday evening.
Behind the trough, a 30.3 inch high drops down over northern Ontario
Thursday and arrives over the Upper Great Lakes by Friday morning.


LSZ162-250800-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
401 PM EDT Sun Aug 24 2025 /301 PM CDT Sun Aug 24 2025/

.LATE THIS AFTERNOON...Northwest winds 15 to 25 knots. Sprinkles.
Waves 3 to 5 feet occasionally to 7 feet subsiding to 2 to
4 feet.
.TONIGHT...Northwest winds 15 to 25 knots. Waves subsiding to
1 to 3 feet, then building to 2 to 4 feet.
.MONDAY...Northwest winds 10 to 20 knots backing west late. Waves
subsiding to calm to 2 feet.
.MONDAY NIGHT...Northwest winds 10 to 20 knots veering north
after midnight. Waves calm to 2 feet.
.TUESDAY...Northwest winds 5 to 15 knots becoming southwest 10 to
20 knots by mid afternoon. Waves calm to 2 feet.
.TUESDAY NIGHT...Southwest winds 10 to 20 knots. Waves building
to 1 to 3 feet.
.WEDNESDAY...Southwest winds 15 to 25 knots. A chance of showers
by mid afternoon. Waves building to 2 to 4 feet, then subsiding
to 1 to 3 feet.
.WEDNESDAY NIGHT...West winds 10 to 20 knots veering northeast
after midnight. A chance of showers through midnight. Waves
subsiding to calm to 2 feet, then building to 1 to 3 feet.
.THURSDAY...Northeast winds 10 to 20 knots becoming east 5 to
15 knots. Waves building to 2 to 4 feet, then subsiding to calm
to 2 feet.
.FRIDAY...East winds 5 to 15 knots. Waves calm to 2 feet.

$$

LSZ263-250800-
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-
401 PM EDT Sun Aug 24 2025

.LATE THIS AFTERNOON...Northwest winds 15 to 25 knots. A slight
chance of waterspouts. Scattered showers. Waves 3 to 6 feet
occasionally to 8 feet.
.TONIGHT...Northwest winds 15 to 25 knots veering north after
midnight. Sprinkles through midnight. Waves 3 to 5 feet
occasionally to 7 feet.
.MONDAY...North winds 15 to 25 knots becoming northwest 10 to
20 knots in the afternoon, then becoming west 5 to 15 knots late.
Waves building to 3 to 6 feet occasionally to 8 feet, then
subsiding to 1 to 3 feet.
.MONDAY NIGHT...North winds 5 to 15 knots. Waves subsiding to
calm to 2 feet.
.TUESDAY...Northwest winds 5 to 15 knots becoming southwest 10 to
20 knots by mid afternoon. Waves calm to 2 feet.
.TUESDAY NIGHT...Southwest winds 10 to 20 knots increasing to
15 to 25 knots after midnight. Waves building to 2 to 4 feet.
.WEDNESDAY...West winds 20 to 30 knots. A chance of showers.
Waves building to 3 to 6 feet occasionally to 8 feet.
.WEDNESDAY NIGHT...West winds 10 to 20 knots veering northeast
after midnight. A chance of showers through midnight. Waves
subsiding to 1 to 3 feet, then building to 2 to 4 feet.
.THURSDAY...Northeast winds 10 to 20 knots becoming east 5 to
15 knots. Waves subsiding to calm to 2 feet.
.FRIDAY...East winds 5 to 15 knots veering south. Waves calm to
2 feet.

$$

LSZ264-250800-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
401 PM EDT Sun Aug 24 2025

.LATE THIS AFTERNOON...Northwest winds 15 to 25 knots. Scattered
showers. Waves 3 to 6 feet occasionally to 8 feet.
.TONIGHT...Northwest winds 15 to 25 knots veering north late.
Sprinkles through midnight. Waves subsiding to 3 to 5 feet
occasionally to 7 feet, then building to 4 to 7 feet occasionally
to 9 feet.
.MONDAY...North winds 15 to 25 knots backing northwest in the
afternoon, then diminishing to 10 to 20 knots late. Waves
subsiding to 2 to 4 feet.
.MONDAY NIGHT...North winds 10 to 20 knots diminishing to 5 to
15 knots after midnight. Waves subsiding to 1 to 3 feet.
.TUESDAY...Northwest winds 5 to 15 knots becoming west 10 to
20 knots by mid afternoon. Waves subsiding to calm to 2 feet.
.TUESDAY NIGHT...Southwest winds 10 to 20 knots increasing to
15 to 25 knots after midnight. Waves building to 2 to 4 feet.
.WEDNESDAY...West winds 20 to 30 knots. A chance of showers.
Waves building to 3 to 6 feet occasionally to 8 feet.
.WEDNESDAY NIGHT...North winds 10 to 20 knots veering northeast
after midnight. Waves subsiding to 1 to 3 feet.
.THURSDAY...Northeast winds 10 to 20 knots becoming east 5 to
15 knots. Waves subsiding to calm to 2 feet.
.FRIDAY...East winds 5 to 15 knots veering south. Waves calm to
2 feet.

$$

LSZ265-250800-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
401 PM EDT Sun Aug 24 2025

.LATE THIS AFTERNOON...Northwest winds 20 to 30 knots. A chance
of waterspouts. Scattered showers. Waves 3 to 6 feet occasionally
to 8 feet.
.TONIGHT...Northwest winds 20 to 30 knots. A slight chance of
waterspouts through midnight. Scattered showers. Waves subsiding
to 3 to 6 feet occasionally to 8 feet.
.MONDAY...Northwest winds 20 to 30 knots diminishing to 15 to
25 knots late. Waves building to 4 to 7 feet occasionally to
9 feet, then subsiding to 3 to 5 feet occasionally to 7 feet.
.MONDAY NIGHT...Northwest winds 10 to 20 knots veering north
after midnight. Waves subsiding to 1 to 3 feet.
.TUESDAY...North winds 10 to 20 knots backing northwest by mid
afternoon. Waves subsiding to calm to 2 feet.
.TUESDAY NIGHT...West winds 10 to 20 knots backing southwest
after midnight. Waves calm to 2 feet.
.WEDNESDAY...West winds 15 to 25 knots. Waves calm to 2 feet.
.WEDNESDAY NIGHT...Northwest winds 10 to 20 knots veering
northeast after midnight. A chance of showers. Waves building to
1 to 3 feet.
.THURSDAY...Northeast winds 10 to 20 knots diminishing to 5 to
15 knots. Waves subsiding to calm to 2 feet.
.FRIDAY...East winds 5 to 15 knots veering south. Waves calm to
2 feet.

$$

LSZ266-250800-
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-
401 PM EDT Sun Aug 24 2025

.LATE THIS AFTERNOON...Northwest winds 20 to 30 knots. A chance
of waterspouts. Numerous showers. Waves 4 to 8 feet occasionally
to 10 feet.
.TONIGHT...Northwest winds 20 to 30 knots increasing to 30 knots
with a few gale force gusts to 35 knots possible late. A slight
chance of waterspouts through midnight. Scattered showers. Waves
subsiding to 4 to 8 feet occasionally to 10 feet.
.MONDAY...Northwest winds to 30 knots with a few gale force gusts
to 35 knots possible diminishing to 20 to 30 knots in the
afternoon. Waves building to 5 to 9 feet occasionally to 11 feet.
.MONDAY NIGHT...Northwest winds 15 to 25 knots veering north
after midnight, then diminishing to 10 to 20 knots late. Waves
subsiding to 2 to 4 feet.
.TUESDAY...North winds 10 to 20 knots backing northwest by mid
afternoon. Waves subsiding to 1 to 3 feet.
.TUESDAY NIGHT...West winds 5 to 15 knots becoming southwest
10 to 20 knots after midnight. Waves subsiding to calm to 2 feet,
then building to 1 to 3 feet.
.WEDNESDAY...Southwest winds 15 to 25 knots veering west by mid
afternoon. A chance of showers by mid afternoon. Waves building
to 3 to 5 feet occasionally to 7 feet.
.WEDNESDAY NIGHT...Northwest winds 10 to 20 knots veering
northeast after midnight. A chance of showers. Waves subsiding to
1 to 3 feet.
.THURSDAY...Northeast winds 10 to 20 knots diminishing to 5 to
15 knots. Waves subsiding to calm to 2 feet.
.FRIDAY...East winds 5 to 15 knots veering south. Waves calm to
2 feet.

$$

LSZ267-250800-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
401 PM EDT Sun Aug 24 2025

.LATE THIS AFTERNOON...Northwest winds 20 to 30 knots. A slight
chance of waterspouts. Scattered showers. Waves 4 to 7 feet
occasionally to 9 feet.
.TONIGHT...Northwest winds 20 to 30 knots. Scattered showers.
Waves building to 4 to 8 feet occasionally to 10 feet.
.MONDAY...Northwest winds 20 to 30 knots. Waves building to 5 to
9 feet occasionally to 11 feet.
.MONDAY NIGHT...Northwest winds 20 to 30 knots becoming north
15 to 25 knots after midnight, then diminishing to 10 to 20 knots
late. Waves subsiding to 2 to 4 feet.
.TUESDAY...North winds 10 to 20 knots becoming northwest 15 to
25 knots by mid afternoon. Waves subsiding to 1 to 3 feet.
.TUESDAY NIGHT...West winds 10 to 20 knots backing southwest
after midnight. Waves subsiding to calm to 2 feet, then building
to 1 to 3 feet.
.WEDNESDAY...Southwest winds 15 to 25 knots veering west by mid
afternoon. A chance of showers by mid afternoon. Waves building
to 2 to 4 feet, then subsiding to 1 to 3 feet.
.WEDNESDAY NIGHT...Northwest winds 10 to 20 knots veering north
after midnight. A chance of showers. Waves 1 to 3 feet.
.THURSDAY...Northeast winds 10 to 20 knots. Waves building to
2 to 4 feet, then subsiding to calm to 2 feet.
.FRIDAY...North winds 10 to 20 knots veering south. Waves calm to
2 feet.

$$

LSZ261-250200-
MAFOR 2421/
Superior West 13730 11820 13720 11710. Waves 3 to 5 feet
subsiding to 2 to 4 feet tonight. Waves 2 to 4 feet subsiding to
1 to 3 feet Monday.

Superior North Central 11730 19736 13730 11740 11840 12730. Waves
3 to 6 feet tonight. Waves 4 to 7 feet subsiding to 3 to 6 feet
Monday.

Superior South Central 11746 11740 19746 12730 12740 12730. A
chance of waterspouts early this evening. Waves 3 to 6 feet
building to 4 to 7 feet tonight. Waves 5 to 8 feet Monday.

Superior East 12740 19746 11730 19736 14740 11740. Waves 6 to 9
feet.

$$

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