829
FZUS63 KMQT 210801
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
401 AM 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 will remain over the lake until at
least Thursday afternoon. By Friday morning, the high will shift to
the southern portions of the Great Lakes basin, eroded to 30.0
inches by a 29.7 inch low over Manitoba to the northwest and by
Hurricane Erin at 28.3 inches over the open waters of the Atlantic
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
Manitoba 29.7 inch low slides over northern Ontario. This low
deepens to 29.6 inches over central Ontario, then lifts toward James
Bay by late Saturday at 29.5 inches. This low will slowly weaken to
29.6 inches Sunday and Monday as it moves into Quebec while 30.2
inch high pressure stretches over the Great Plains.


LSZ162-212000-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
401 AM EDT Thu Aug 21 2025 /301 AM CDT Thu Aug 21 2025/

.EARLY THIS MORNING...South winds 5 to 15 knots. Patchy fog.
Waves calm to 2 feet.
.TODAY...South winds 5 to 15 knots backing east late. Patchy fog
through early afternoon. Waves calm to 2 feet.
.TONIGHT...Southeast winds 5 to 15 knots veering southwest after
midnight. A chance of showers and thunderstorms. Waves calm to
2 feet.
.FRIDAY...Southwest winds 10 to 20 knots. A chance of showers and
thunderstorms. Waves calm to 2 feet.
.FRIDAY NIGHT...West winds 10 to 20 knots increasing to 15 to
25 knots after midnight. Waves building to 1 to 3 feet.
.SATURDAY...West winds 15 to 25 knots increasing to 20 to
30 knots by mid afternoon. Waves building to 2 to 4 feet.
.SATURDAY NIGHT...Northwest winds 20 to 30 knots diminishing to
15 to 25 knots after midnight. Waves 2 to 4 feet.
.SUNDAY...Northwest winds 15 to 25 knots diminishing to 10 to
20 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.

$$

LSZ263-212000-
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 Thu Aug 21 2025

.EARLY THIS MORNING...South winds less than 10 knots. Waves calm
to 2 feet.
.TODAY...Southwest winds less than 10 knots increasing to 5 to
15 knots in the afternoon, then backing south late. Waves calm to
2 feet.
.TONIGHT...Southeast winds 5 to 15 knots veering southwest after
midnight, then increasing to 10 to 20 knots late. A chance of
showers and thunderstorms. Waves building to 1 to 3 feet.
.FRIDAY...Southwest winds 10 to 20 knots. A chance of showers and
thunderstorms. Waves 1 to 3 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. Waves building to 3 to
6 feet occasionally to 8 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots veering northwest
after midnight. Waves subsiding to 3 to 5 feet occasionally to
7 feet.
.SUNDAY...Northwest winds 15 to 25 knots veering north. Waves
subsiding to 2 to 4 feet.
.MONDAY...North winds 15 to 25 knots diminishing to 5 to
15 knots. Waves building to 3 to 5 feet occasionally to 7 feet,
then subsiding to calm to 2 feet.

$$

LSZ264-212000-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
401 AM EDT Thu Aug 21 2025

.EARLY THIS MORNING...Southwest winds less than 10 knots. Waves
calm to 2 feet.
.TODAY...Southwest winds 5 to 15 knots backing south in the
afternoon. Waves calm to 2 feet.
.TONIGHT...South winds 5 to 15 knots becoming southwest 10 to
20 knots late. A chance of showers and thunderstorms. Waves calm
to 2 feet.
.FRIDAY...Southwest winds 10 to 20 knots. A chance of showers and
thunderstorms. Waves building to 1 to 3 feet.
.FRIDAY NIGHT...Southwest winds 10 to 20 knots veering west after
midnight. A slight chance of showers and thunderstorms 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 3 to 6 feet
occasionally to 8 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots veering northwest
after midnight. Waves subsiding to 3 to 5 feet occasionally to
7 feet.
.SUNDAY...Northwest winds 15 to 25 knots. Waves building to 3 to
6 feet occasionally to 8 feet.
.MONDAY...North winds 15 to 25 knots diminishing to 5 to
15 knots. Waves subsiding to 1 to 3 feet.

$$

LSZ265-212000-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
401 AM EDT Thu Aug 21 2025

.EARLY THIS MORNING...Southwest winds less than 10 knots. Patchy
fog. Waves calm to 2 feet.
.TODAY...South winds 5 to 15 knots backing southeast in the
afternoon. Waves calm to 2 feet.
.TONIGHT...Southeast winds 10 to 20 knots becoming south 5 to
15 knots after midnight, then becoming southwest 10 to 20 knots
late. A slight chance of showers and thunderstorms after
midnight. Waves calm to 2 feet.
.FRIDAY...Southwest winds 10 to 20 knots veering west in the
afternoon. A chance of showers and thunderstorms. Waves calm to
2 feet.
.FRIDAY NIGHT...Southwest winds 5 to 15 knots becoming west 10 to
20 knots after midnight. A slight chance of showers and
thunderstorms through midnight. Waves calm to 2 feet.
.SATURDAY...West winds 15 to 25 knots increasing to 20 to
30 knots by mid afternoon. Waves building to 2 to 4 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots. Waves subsiding to
1 to 3 feet, then building to 2 to 4 feet.
.SUNDAY...Northwest winds 15 to 25 knots. Waves building to 3 to
5 feet occasionally to 7 feet.
.MONDAY...Northwest winds 20 to 30 knots diminishing to 10 to
20 knots. Waves building to 3 to 6 feet occasionally to 8 feet,
then subsiding to 1 to 3 feet.

$$

LSZ266-212000-
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 Thu Aug 21 2025

.EARLY THIS MORNING...North winds 5 to 15 knots. Patchy dense
fog. Waves calm to 2 feet.
.TODAY...South winds 5 to 15 knots backing east late. Waves calm
to 2 feet.
.TONIGHT...Southeast winds 5 to 15 knots becoming south 10 to
20 knots after midnight, then veering southwest late. A slight
chance of showers and thunderstorms after midnight. Waves calm to
2 feet.
.FRIDAY...Southwest winds 10 to 20 knots. A chance of showers and
thunderstorms. Waves building to 1 to 3 feet.
.FRIDAY NIGHT...Southwest winds 5 to 15 knots becoming west 10 to
20 knots after midnight. A chance of showers and thunderstorms.
Waves subsiding to calm to 2 feet, then building to 1 to 3 feet.
.SATURDAY...West winds 15 to 25 knots. Waves building to 3 to
5 feet occasionally to 7 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots. Waves subsiding to
2 to 4 feet, then building to 3 to 5 feet occasionally to 7 feet.
.SUNDAY...Northwest winds 15 to 25 knots. 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 building to 4 to 7 feet occasionally to 9 feet,
then subsiding to 2 to 4 feet.

$$

LSZ267-212000-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
401 AM EDT Thu Aug 21 2025

.EARLY THIS MORNING...North winds 5 to 15 knots. Waves calm to
2 feet.
.TODAY...Northwest winds 5 to 15 knots veering north late. Waves
calm to 2 feet.
.TONIGHT...Southeast winds 5 to 15 knots veering south after
midnight, then increasing to 10 to 20 knots late. Waves calm to
2 feet.
.FRIDAY...Southwest winds 10 to 20 knots. 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 calm to 2 feet.
.SATURDAY...West winds 10 to 20 knots increasing to 15 to
25 knots by mid afternoon. Waves building to 1 to 3 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots. Waves building to
2 to 4 feet.
.SUNDAY...Northwest winds 15 to 25 knots. A chance of showers.
Waves building to 3 to 6 feet occasionally to 8 feet.
.MONDAY...Northwest winds 15 to 25 knots veering north. Waves
subsiding to 2 to 4 feet.

$$

LSZ261-211400-
MAFOR 2109/
Superior West 13400 13300 11410 11510. A chance of showers
overnight. Waves 2 feet or less.

Superior North Central 11500 19504 14400 11400 12410. Waves 2
feet or less.

Superior South Central 11600 12400 13300 11400 11510. Waves 1
foot or less.

Superior East 11800 11600 19604 11600 11700 11100 11300 11400
11410. 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