276
FZUS63 KMQT 200801
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
400 AM EDT Thu Aug 20 2026

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...

30.0 inch high pressure expands into the rest of the Great Lakes at
30.1 inches today. A weakening shortwave low of 29.8 inches moves
towards western Lake Superior today, eventually bringing 29.9 inch
troughing back over the lake tonight. Friday into this weekend, a
low pressure of around 29.8 inches transits across northern Ontario,
reinforcing 29.9 inch troughing over Lake Superior Friday into
Saturday morning. This is quickly followed by 30.1 inch ridging for
the latter part of the weekend into early next week via a 30.2 inch
parent high from Canada that drops down into the Ohio River Valley
by late Monday.



LSZ162-202000-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
400 AM EDT Thu Aug 20 2026 /300 AM CDT Thu Aug 20 2026/

.EARLY THIS MORNING...South winds less than 10 knots. A slight
chance of showers. Waves calm to 2 feet.
.TODAY...East winds 5 to 15 knots veering southeast in the
afternoon, then becoming east 10 to 20 knots late. A chance of
showers through early afternoon. A slight chance of
thunderstorms. Showers by mid afternoon. Waves calm to 2 feet.
.TONIGHT...East winds 5 to 15 knots backing northeast after
midnight. A chance of showers and a slight chance of
thunderstorms through midnight. Waves calm to 2 feet.
.FRIDAY...Northeast winds 5 to 15 knots backing north in the
afternoon, then backing southwest late. Waves calm to 2 feet.
.FRIDAY NIGHT...West winds 5 to 15 knots becoming northwest 10 to
20 knots after midnight. Waves calm to 2 feet.
.SATURDAY...Northwest winds 10 to 20 knots. Waves calm to 2 feet.
.SATURDAY NIGHT...North winds 10 to 20 knots diminishing to 5 to
15 knots after midnight. Waves calm to 2 feet.
.SUNDAY...North winds 5 to 15 knots veering northeast. Waves calm
to 2 feet.
.MONDAY...East winds 5 to 15 knots. Waves calm to 2 feet.

$$

LSZ263-202000-
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-
400 AM EDT Thu Aug 20 2026

.EARLY THIS MORNING...South winds 5 to 15 knots. Patchy dense
fog. Waves calm to 2 feet.
.TODAY...Southwest winds 5 to 15 knots backing southeast in the
afternoon, then backing east late. Patchy dense fog through early
afternoon. A slight chance of showers through early afternoon,
then showers likely and a slight chance of thunderstorms by mid
afternoon. Waves calm to 2 feet.
.TONIGHT...East winds 5 to 15 knots veering southeast after
midnight, then backing northeast late. A slight chance of
thunderstorms through midnight. A chance of showers. Waves calm
to 2 feet.
.FRIDAY...North winds 5 to 15 knots backing west late. A slight
chance of showers through early afternoon. Waves calm to 2 feet.
.FRIDAY NIGHT...West winds 5 to 15 knots increasing to 10 to
20 knots after midnight. A slight chance of showers and
thunderstorms after midnight. Waves calm to 2 feet.
.SATURDAY...Northwest winds 10 to 20 knots becoming west 5 to
15 knots by mid afternoon. Waves calm to 2 feet.
.SATURDAY NIGHT...North winds 5 to 15 knots increasing to 10 to
20 knots after midnight. Waves calm to 2 feet.
.SUNDAY...North winds 5 to 15 knots veering south. Waves calm to
2 feet.
.MONDAY...South winds 5 to 15 knots increasing to 10 to 20 knots.
Waves calm to 2 feet.

$$

LSZ264-202000-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
400 AM EDT Thu Aug 20 2026

.EARLY THIS MORNING...South winds 5 to 15 knots. Patchy dense
fog. Waves calm to 2 feet.
.TODAY...Southwest winds 5 to 15 knots becoming south less than
10 knots in the afternoon, then becoming southeast 5 to 15 knots
late. A chance of showers. Waves calm to 2 feet.
.TONIGHT...Southeast winds 5 to 15 knots backing east late. A
chance of showers. Waves building to 1 to 3 feet.
.FRIDAY...Northeast winds 5 to 15 knots backing north in the
afternoon. A slight chance of showers through early afternoon.
Waves subsiding to calm to 2 feet.
.FRIDAY NIGHT...West winds 5 to 15 knots. Waves calm to 2 feet.
.SATURDAY...Northwest winds 10 to 20 knots. Waves calm to 2 feet.
.SATURDAY NIGHT...North winds 10 to 20 knots. Waves building to
1 to 3 feet.
.SUNDAY...North winds 10 to 20 knots becoming west 5 to 15 knots.
Waves subsiding to calm to 2 feet.
.MONDAY...South winds 5 to 15 knots. Waves calm to 2 feet.

$$

LSZ265-202000-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
400 AM EDT Thu Aug 20 2026

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

$$

LSZ266-202000-
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-
400 AM EDT Thu Aug 20 2026

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

$$

LSZ267-202000-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
400 AM EDT Thu Aug 20 2026

.EARLY THIS MORNING...South winds 5 to 15 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 5 to 15 knots increasing to 10 to
20 knots after midnight, then becoming south 15 to 25 knots late.
A chance of showers. A slight chance of thunderstorms after
midnight. Waves building to 1 to 3 feet.
.FRIDAY...South winds 15 to 25 knots diminishing to 10 to
20 knots in the afternoon. A chance of showers. A slight chance
of thunderstorms by mid afternoon. Waves building to 2 to 4 feet,
then subsiding to calm to 2 feet.
.FRIDAY NIGHT...South winds 10 to 20 knots veering northwest
after midnight. A slight chance of thunderstorms through
midnight. A chance of showers. Waves calm to 2 feet.
.SATURDAY...Northwest winds 10 to 20 knots increasing to 15 to
25 knots by mid afternoon. Waves building to 2 to 4 feet.
.SATURDAY NIGHT...Northwest winds 20 to 30 knots veering north
after midnight. Waves building to 3 to 5 feet occasionally to
7 feet.
.SUNDAY...Northwest winds 20 to 30 knots diminishing to 10 to
20 knots. Waves subsiding to calm to 2 feet.
.MONDAY...Northwest winds 10 to 20 knots backing southwest. Waves
calm to 2 feet.

$$

LSZ261-201400-
MAFOR 2009/
Superior West 11400 11500 11300 11306 12210 11200 11100. Waves 1
foot or less.

Superior North Central 12400 11500 11400 14310. A chance of
showers this afternoon and tonight. Waves 1 foot or less today.
Waves 1 to 3 feet tonight.

Superior South Central 12510 11400 11310 12320 11330 11436. Waves
1 foot or less today. Waves 1 to 3 feet tonight.

Superior East 13400 12300 12310 11320. A chance of showers
overnight. 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