946
FZUS63 KMQT 190201
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
1000 PM EDT Tue Aug 18 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...

Weak 29.9 inch ridging over Lake Superior tonight and early
Wednesday morning builds to 30.0 inches Wednesday afternoon as high
pressure over the Canadian Prairies and Northern Plains tonight
moves into the Upper Great Lakes. This high then expands into the
rest of the Great Lakes by Thursday as it strengthens to 30.1
inches. Friday into the weekend, a low pressure of around 29.8
inches transits across northern Ontario, bringing 29.9 inch
troughing over Lake Superior Friday into Saturday. 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.



LSZ162-190800-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
1000 PM EDT Tue Aug 18 2026 /900 PM CDT Tue Aug 18 2026/

.REST OF TONIGHT...West winds 10 to 20 knots diminishing to 5 to
15 knots after midnight. Waves calm to 2 feet.
.WEDNESDAY...West winds 5 to 15 knots backing southwest in the
afternoon. Waves calm to 2 feet.
.WEDNESDAY NIGHT...Southwest winds 5 to 15 knots backing
northeast after midnight. Waves calm to 2 feet.
.THURSDAY...East winds 5 to 15 knots. A chance of showers. A
slight chance of thunderstorms by mid afternoon. Waves calm to
2 feet.
.THURSDAY NIGHT...East winds 5 to 15 knots backing northeast
after midnight. A slight chance of thunderstorms through
midnight. A chance of showers. Waves calm to 2 feet.
.FRIDAY...Northeast winds 5 to 15 knots backing north by mid
afternoon. Waves calm to 2 feet.
.FRIDAY NIGHT...West winds 5 to 15 knots veering northwest after
midnight. Waves calm to 2 feet.
.SATURDAY...Northwest winds 5 to 15 knots veering north. Waves
calm to 2 feet.
.SUNDAY...East winds 5 to 15 knots. Waves calm to 2 feet.

$$

LSZ263-190800-
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-
1000 PM EDT Tue Aug 18 2026

.REST OF TONIGHT...West winds 5 to 15 knots veering northwest
late. Waves 1 to 3 feet subsiding to calm to 2 feet.
.WEDNESDAY...Northwest winds 5 to 15 knots backing southwest
late. Waves calm to 2 feet.
.WEDNESDAY NIGHT...Southwest winds 5 to 15 knots becoming south
less than 10 knots after midnight. Waves calm to 2 feet.
.THURSDAY...South winds less than 10 knots becoming southeast
5 to 15 knots by mid afternoon. A slight chance of showers. A
slight chance of thunderstorms by mid afternoon. Waves calm to
2 feet.
.THURSDAY NIGHT...Southeast winds 5 to 15 knots backing east
after midnight. A slight chance of thunderstorms through
midnight. A chance of showers. Waves calm to 2 feet.
.FRIDAY...Northeast winds 5 to 15 knots backing north by mid
afternoon. Waves calm to 2 feet.
.FRIDAY NIGHT...West winds 5 to 15 knots veering northwest after
midnight. Waves calm to 2 feet.
.SATURDAY...Northwest winds 5 to 15 knots veering north. Waves
calm to 2 feet.
.SUNDAY...North winds 5 to 15 knots veering southeast. Waves calm
to 2 feet.

$$

LSZ264-190800-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
1000 PM EDT Tue Aug 18 2026

.REST OF TONIGHT...West winds 5 to 15 knots veering northwest
after midnight. Waves 1 to 3 feet subsiding to calm to 2 feet.
.WEDNESDAY...Northwest winds 5 to 15 knots backing southwest
late. Waves calm to 2 feet.
.WEDNESDAY NIGHT...Southwest winds 5 to 15 knots becoming south
less than 10 knots after midnight. Waves calm to 2 feet.
.THURSDAY...Southeast winds less than 10 knots increasing to 5 to
15 knots by mid afternoon. Waves calm to 2 feet.
.THURSDAY NIGHT...Southeast winds 5 to 15 knots. A slight chance
of showers. Waves calm to 2 feet.
.FRIDAY...East winds 5 to 15 knots. Waves calm to 2 feet.
.FRIDAY NIGHT...West winds 5 to 15 knots veering northwest after
midnight. Waves calm to 2 feet.
.SATURDAY...Northwest winds 5 to 15 knots veering north. Waves
calm to 2 feet.
.SUNDAY...North winds 5 to 15 knots veering south. Waves calm to
2 feet.

$$

LSZ265-190800-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
1000 PM EDT Tue Aug 18 2026

.REST OF TONIGHT...West winds 15 to 25 knots. Waves calm to
2 feet.
.WEDNESDAY...Northwest winds 10 to 20 knots veering north in the
afternoon, then becoming northeast 5 to 15 knots late. Waves calm
to 2 feet.
.WEDNESDAY NIGHT...South winds 5 to 15 knots increasing to 10 to
20 knots after midnight, then veering southwest late. Waves calm
to 2 feet.
.THURSDAY...Southwest winds 5 to 15 knots becoming southeast
10 to 20 knots by mid afternoon. A slight chance of showers by
mid afternoon. Waves calm to 2 feet.
.THURSDAY NIGHT...Southeast winds 10 to 20 knots veering south
after midnight. A chance of showers. Waves calm to 2 feet.
.FRIDAY...Southeast winds 10 to 20 knots backing east by mid
afternoon. A chance of showers. Waves calm to 2 feet.
.FRIDAY NIGHT...Northwest winds 10 to 20 knots. Waves calm to
2 feet.
.SATURDAY...Northwest winds 20 to 30 knots becoming north 15 to
25 knots. Waves building to 3 to 5 feet occasionally to 7 feet,
then subsiding to 2 to 4 feet.
.SUNDAY...North winds 15 to 25 knots becoming south 10 to
20 knots. Waves subsiding to calm to 2 feet.

$$

LSZ266-190800-
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-
1000 PM EDT Tue Aug 18 2026

.REST OF TONIGHT...West winds 10 to 20 knots veering northwest
late. Waves 1 to 3 feet subsiding to calm to 2 feet.
.WEDNESDAY...Northwest winds 10 to 20 knots diminishing to 5 to
15 knots in the afternoon. Waves calm to 2 feet.
.WEDNESDAY NIGHT...South winds 5 to 15 knots veering southwest
late. Waves calm to 2 feet.
.THURSDAY...South winds 5 to 15 knots backing southeast by mid
afternoon. Waves calm to 2 feet.
.THURSDAY NIGHT...Southeast winds 5 to 15 knots increasing to
10 to 20 knots after midnight. A chance of showers. A slight
chance of thunderstorms after midnight. Waves calm to 2 feet.
.FRIDAY...Southeast winds 10 to 20 knots backing east by mid
afternoon. A chance of showers. Waves calm to 2 feet.
.FRIDAY NIGHT...Northwest winds 10 to 20 knots. Waves calm to
2 feet.
.SATURDAY...Northwest winds 20 to 30 knots becoming north 15 to
25 knots. Waves building to 3 to 6 feet occasionally to 8 feet,
then subsiding to 2 to 4 feet.
.SUNDAY...North winds 15 to 25 knots becoming northwest 10 to
20 knots. Waves subsiding to calm to 2 feet.

$$

LSZ267-190800-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
1000 PM EDT Tue Aug 18 2026

.REST OF TONIGHT...West winds 10 to 20 knots. Waves calm to
2 feet.
.WEDNESDAY...Northwest winds 10 to 20 knots diminishing to 5 to
15 knots late. Waves calm to 2 feet.
.WEDNESDAY NIGHT...West winds 5 to 15 knots backing south late.
Waves calm to 2 feet.
.THURSDAY...South winds 5 to 15 knots backing northeast by mid
afternoon. Waves calm to 2 feet.
.THURSDAY NIGHT...Southeast winds 5 to 15 knots increasing to
10 to 20 knots after midnight. A chance of showers. Waves calm to
2 feet.
.FRIDAY...Southeast winds 10 to 20 knots. Showers likely. Waves
calm to 2 feet.
.FRIDAY NIGHT...Northwest winds 10 to 20 knots. Waves calm to
2 feet.
.SATURDAY...Northwest winds 10 to 20 knots becoming north 15 to
25 knots. Waves building to 2 to 4 feet.
.SUNDAY...Northwest winds 15 to 25 knots diminishing to 10 to
20 knots. Waves subsiding to calm to 2 feet.

$$

LSZ261-190800-
MAFOR 1903/
Superior West 11610 13710 11600 13510. Waves 1 foot or less.

Superior North Central 11620 13710 11700 11600 12500. Waves 2 to
3 feet overnight. Waves 2 feet or less Wednesday and Wednesday
evening.

Superior South Central 12620 13720 11820 11110 11300. Waves 2
feet or less.

Superior East 12610 12710 13700 11600. Waves 1 to 2 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