451
FZUS63 KMQT 170801
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
401 AM EDT Sun Aug 17 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...

High pressure of 30.3 inches will remain over northern Ontario
through tonight. By Monday morning, the high will shift south of
James Bay while a 29.9 inch low moves over Minnesota, with the low
moving near the lake Monday evening through Tuesday morning. By
Wednesday, high pressure of around 30.1 inches establishes itself
over Lake Superior, weakening to near 30.0 inches by Thursday.
Friday, a 29.6 inch low moving over far northern Ontario will pass a
29.9 inch trough over Lake Superior.


LSZ162-172000-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
401 AM EDT Sun Aug 17 2025 /301 AM CDT Sun Aug 17 2025/

.EARLY THIS MORNING...East winds 20 to 30 knots. Waves 3 to
6 feet occasionally to 8 feet building to 4 to 7 feet
occasionally to 9 feet.
.TODAY...East winds 15 to 25 knots increasing to 20 to 30 knots
in the afternoon. Waves building to 4 to 8 feet occasionally to
10 feet.
.TONIGHT...East winds 15 to 25 knots. A slight chance of showers
through midnight. A chance of thunderstorms. Showers likely after
midnight. Waves subsiding to 2 to 4 feet.
.MONDAY...East winds 15 to 25 knots. Showers through early
afternoon. A chance of thunderstorms. A chance of showers by mid
afternoon. Waves 2 to 4 feet.
.MONDAY NIGHT...Northeast winds 10 to 20 knots. A chance of
showers through midnight. Waves 2 to 4 feet.
.TUESDAY...Northeast winds 10 to 20 knots diminishing to 5 to
15 knots by mid afternoon. Waves subsiding to calm to 2 feet.
.TUESDAY NIGHT...Northeast winds 5 to 15 knots backing north
after midnight. Waves calm to 2 feet.
.WEDNESDAY...South winds 5 to 15 knots veering southwest. Waves
calm to 2 feet.
.THURSDAY...Southwest winds 5 to 15 knots increasing to 10 to
20 knots. Waves calm to 2 feet.

$$

LSZ263-172000-
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 AM EDT Sun Aug 17 2025

.EARLY THIS MORNING...Northeast winds 15 to 25 knots. Waves 4 to
8 feet occasionally to 10 feet.
.TODAY...East winds 15 to 25 knots. Waves subsiding to 3 to
6 feet occasionally to 8 feet, then building to 4 to 7 feet
occasionally to 9 feet.
.TONIGHT...East winds 15 to 25 knots becoming southeast 10 to
20 knots after midnight. A chance of showers. A slight chance of
thunderstorms after midnight. Waves subsiding to 2 to 4 feet.
.MONDAY...Southeast winds 15 to 25 knots backing east late.
Showers and a chance of thunderstorms. Waves building to 3 to
6 feet occasionally to 8 feet.
.MONDAY NIGHT...East winds 10 to 20 knots backing northeast after
midnight. A slight chance of thunderstorms through midnight. A
chance of showers. Waves subsiding to 2 to 4 feet.
.TUESDAY...Northeast winds 10 to 20 knots. Waves subsiding to
1 to 3 feet.
.TUESDAY NIGHT...Northeast winds 5 to 15 knots becoming north
less than 10 knots after midnight. Waves subsiding to calm to
2 feet.
.WEDNESDAY...Northwest winds 5 to 15 knots backing southwest.
Waves calm to 2 feet.
.THURSDAY...Southwest winds 5 to 15 knots increasing to 10 to
20 knots. Waves calm to 2 feet.

$$

LSZ264-172000-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
401 AM EDT Sun Aug 17 2025

.EARLY THIS MORNING...Northeast winds 15 to 25 knots. Waves 4 to
7 feet occasionally to 9 feet.
.TODAY...East winds 15 to 25 knots diminishing to 10 to 20 knots
in the afternoon. Waves subsiding to 2 to 4 feet.
.TONIGHT...East winds 5 to 15 knots increasing to 10 to 20 knots
after midnight, then veering southeast late. A chance of showers
after midnight. Waves subsiding to 1 to 3 feet, then building to
2 to 4 feet.
.MONDAY...Southeast winds 15 to 25 knots increasing to 20 to
30 knots in the afternoon. Showers likely and a slight chance of
thunderstorms. Waves building to 4 to 7 feet occasionally to
9 feet.
.MONDAY NIGHT...East winds 15 to 25 knots diminishing to 10 to
20 knots after midnight. A slight chance of thunderstorms through
midnight. A chance of showers. Waves subsiding to 3 to 5 feet
occasionally to 7 feet.
.TUESDAY...Northeast winds 10 to 20 knots. Waves subsiding to
1 to 3 feet.
.TUESDAY NIGHT...North winds 5 to 15 knots diminishing to less
than 10 knots after midnight. Waves subsiding to calm to 2 feet.
.WEDNESDAY...North winds 5 to 15 knots backing southwest. Waves
calm to 2 feet.
.THURSDAY...Southwest winds 5 to 15 knots becoming south 10 to
20 knots. Waves calm to 2 feet.

$$

LSZ265-172000-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
401 AM EDT Sun Aug 17 2025

.EARLY THIS MORNING...Northeast winds 20 to 30 knots. Waves 3 to
6 feet occasionally to 8 feet building to 4 to 7 feet
occasionally to 9 feet.
.TODAY...East winds 15 to 25 knots diminishing to 10 to 20 knots
in the afternoon. Waves subsiding to 2 to 4 feet.
.TONIGHT...East winds 10 to 20 knots veering southeast after
midnight, then increasing to 15 to 25 knots late. A chance of
showers after midnight. Waves subsiding to 1 to 3 feet.
.MONDAY...Southeast winds 15 to 25 knots increasing to 20 to
30 knots in the afternoon. Showers likely and a chance of
thunderstorms. Waves building to 2 to 4 feet.
.MONDAY NIGHT...Southeast winds 15 to 25 knots becoming east
10 to 20 knots after midnight. A chance of showers and a slight
chance of thunderstorms. Waves subsiding to 1 to 3 feet.
.TUESDAY...Northeast winds 10 to 20 knots increasing to 15 to
25 knots by mid afternoon. Waves 1 to 3 feet.
.TUESDAY NIGHT...North winds 10 to 20 knots diminishing to 5 to
15 knots after midnight. Waves subsiding to calm to 2 feet.
.WEDNESDAY...North winds 5 to 15 knots backing southwest. Waves
calm to 2 feet.
.THURSDAY...Southeast winds 5 to 15 knots veering southwest.
Waves calm to 2 feet.

$$

LSZ266-172000-
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 AM EDT Sun Aug 17 2025

.EARLY THIS MORNING...Northeast winds 20 to 30 knots. Waves 4 to
7 feet occasionally to 9 feet.
.TODAY...Northeast winds 15 to 25 knots diminishing to 5 to
15 knots late. Waves subsiding to 1 to 3 feet.
.TONIGHT...East winds 10 to 20 knots veering southeast after
midnight, then increasing to 15 to 25 knots late. A slight chance
of showers after midnight. Waves subsiding to calm to 2 feet,
then building to 3 to 5 feet occasionally to 7 feet.
.MONDAY...Southeast winds 15 to 25 knots increasing to 20 to
30 knots in the afternoon, then diminishing to 15 to 25 knots
late. A chance of showers. A slight chance of thunderstorms by
mid afternoon. Waves building to 3 to 6 feet occasionally to
8 feet.
.MONDAY NIGHT...Southeast winds 10 to 20 knots backing east after
midnight. Showers likely through midnight. A slight chance of
thunderstorms. A chance of showers after midnight. Waves
subsiding to 2 to 4 feet.
.TUESDAY...East winds 10 to 20 knots backing northeast by mid
afternoon. Waves subsiding to 1 to 3 feet.
.TUESDAY NIGHT...North winds 10 to 20 knots. Waves subsiding to
calm to 2 feet.
.WEDNESDAY...North winds 5 to 15 knots backing southwest. Waves
calm to 2 feet.
.THURSDAY...South winds 5 to 15 knots. Waves calm to 2 feet.

$$

LSZ267-172000-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
401 AM EDT Sun Aug 17 2025

.EARLY THIS MORNING...Northeast winds 20 to 30 knots. Waves 4 to
7 feet occasionally to 9 feet.
.TODAY...Northeast winds 10 to 20 knots. Waves subsiding to calm
to 2 feet.
.TONIGHT...Northeast winds 10 to 20 knots becoming southeast
15 to 25 knots after midnight. Waves building to 2 to 4 feet.
.MONDAY...Southeast winds 15 to 25 knots. A chance of showers and
a slight chance of thunderstorms by mid afternoon. Waves 2 to
4 feet.
.MONDAY NIGHT...Southeast winds 15 to 25 knots. Showers likely
through midnight. A chance of thunderstorms. A chance of showers
after midnight. Waves building to 3 to 5 feet occasionally to
7 feet, then subsiding to 2 to 4 feet.
.TUESDAY...East winds 10 to 20 knots. A chance of showers. Waves
subsiding to calm to 2 feet.
.TUESDAY NIGHT...Northeast winds 10 to 20 knots. Waves calm to
2 feet.
.WEDNESDAY...North winds 10 to 20 knots diminishing to 5 to
15 knots. Waves calm to 2 feet.
.THURSDAY...Southwest winds 5 to 15 knots backing south. Waves
calm to 2 feet.

$$

LSZ261-171400-
MAFOR 1709/
Superior West 12240 11230 11240 13230 11330. A chance of showers
overnight. Waves 5 to 8 feet.

Superior North Central 11130 11230 13220 11210 11220 11320. Waves
4 to 7 feet subsiding to 2 to 4 feet today. Waves 1 to 3 feet
tonight.

Superior South Central 12130 11120 12220 11210 11220 11320. Waves
4 to 7 feet subsiding to 3 to 5 feet today. Waves 2 to 4 feet
tonight.

Superior East 12130 12120 12110 11220 11330. Waves 5 to 7 feet
subsiding to 2 to 4 feet today. Waves 1 to 3 feet building to 2
to 4 feet tonight.

$$

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