


Great Lakes Forecast
Issued by NWS
Issued by NWS
442 FZUS63 KMQT 172001 GLFLS Open Lake Forecast for Lake Superior National Weather Service Marquette MI 401 PM EDT Fri Oct 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... A 29.4 inch low will lift through Manitoba today while deepening to 29.2 inches. It will continue onto Hudson Bay through Saturday afternoon, deepening further to 29.1 inches. As a result, a 29.5 inch trough will be pulled over Lake Superior this afternoon and tonight, followed by a second 29.5 inch through Saturday. A secondary low develops over the Mid Mississippi Valley at the base of this secondary trough late in the day Saturday, then deepens to at least 29.3 inches on Sunday as it crosses Lower Michigan. This low reaches James Bay Sunday night while a weak 29.7 inch ridge briefly extends over Lake Superior. Another low pressure at 29.5 inches develops upstream over the Northern Plains, tracking east over the region Monday night before coalescing into a compact 29.4 inch low over the Upper Great Lakes Tuesday morning. LSZ162-180800- Lake Superior west of a line from Saxon Harbor WI to Grand Portage MN beyond 5NM- 401 PM EDT Fri Oct 17 2025 /301 PM CDT Fri Oct 17 2025/ .LATE THIS AFTERNOON...Southwest winds 15 to 25 knots. A slight chance of showers. Waves 1 to 3 feet. .TONIGHT...Southwest winds 15 to 25 knots diminishing to 10 to 20 knots after midnight. Waves building to 2 to 4 feet, then subsiding to 1 to 3 feet. .SATURDAY...Southwest winds 5 to 15 knots becoming west 10 to 20 knots in the afternoon. Waves subsiding to calm to 2 feet. .SATURDAY NIGHT...Northwest winds 10 to 20 knots increasing to 15 to 25 knots after midnight. A slight chance of showers. Waves building to 1 to 3 feet. .SUNDAY...Northwest winds 15 to 25 knots. Waves building to 2 to 4 feet, then subsiding to 1 to 3 feet. .SUNDAY NIGHT...West winds 10 to 20 knots becoming southwest 5 to 15 knots after midnight. Waves subsiding to calm to 2 feet. .MONDAY...South winds 10 to 20 knots increasing to 15 to 25 knots by mid afternoon. A chance of showers through early afternoon, then showers likely by mid afternoon. Waves building to 1 to 3 feet. .MONDAY NIGHT...West winds 15 to 25 knots becoming northwest 20 to 30 knots after midnight. Showers likely. Waves building to 2 to 4 feet. .TUESDAY...Northwest gales to 35 knots diminishing to 15 to 25 knots. A chance of rain showers. Waves building to 3 to 6 feet occasionally to 8 feet, then subsiding to calm to 2 feet. .WEDNESDAY...Southwest winds 5 to 15 knots increasing to 10 to 20 knots. Waves calm to 2 feet. $$ LSZ263-180800- Lake Superior from Saxon Harbor WI to Upper Entrance to Portage Canal MI 5NM off shore to the US/Canadian border including Isle Royale National Park- 401 PM EDT Fri Oct 17 2025 .LATE THIS AFTERNOON...South winds 10 to 20 knots. A slight chance of showers. Waves 1 to 3 feet. .TONIGHT...Southwest winds 15 to 25 knots diminishing to 10 to 20 knots late. A slight chance of showers through midnight. Waves building to 3 to 5 feet occasionally to 7 feet, then subsiding to 2 to 4 feet. .SATURDAY...Southwest winds 5 to 15 knots veering west in the afternoon. Waves subsiding to calm to 2 feet. .SATURDAY NIGHT...Northwest winds 5 to 15 knots increasing to 15 to 25 knots. A slight chance of showers. Waves building to 3 to 5 feet occasionally to 7 feet. .SUNDAY...Northwest winds 20 to 30 knots. A slight chance of showers through early afternoon. Waves building to 3 to 6 feet occasionally to 8 feet. .SUNDAY NIGHT...Northwest winds 15 to 25 knots becoming west 5 to 15 knots after midnight. Waves subsiding to calm to 2 feet. .MONDAY...South winds 15 to 25 knots backing southeast by mid afternoon. A chance of showers through early afternoon, then showers likely by mid afternoon. Waves building to 2 to 4 feet. .MONDAY NIGHT...West winds 15 to 25 knots becoming northwest gales to 35 knots after midnight. Showers likely. Waves subsiding to 1 to 3 feet, then building to 3 to 5 feet occasionally to 7 feet. .TUESDAY...Northwest gales to 35 knots veering north. Rain showers likely. Waves building to 6 to 9 feet occasionally to 11 feet, then subsiding to 3 to 5 feet occasionally to 7 feet. .WEDNESDAY...West winds 15 to 25 knots becoming southwest 10 to 20 knots. Waves subsiding to calm to 2 feet, then building to 1 to 3 feet. $$ LSZ264-180800- Lake Superior from Upper Entrance to Portage Canal to Manitou Island MI 5NM off shore to the US/Canadian Border- 401 PM EDT Fri Oct 17 2025 .LATE THIS AFTERNOON...South winds 10 to 20 knots. A chance of showers and a slight chance of thunderstorms. Waves 2 to 4 feet. .TONIGHT...South winds 15 to 25 knots veering southwest after midnight, then diminishing to 10 to 20 knots late. A chance of showers through midnight. Waves building to 3 to 5 feet occasionally to 7 feet, then subsiding to 2 to 4 feet. .SATURDAY...West winds 5 to 15 knots. Waves subsiding to calm to 2 feet. .SATURDAY NIGHT...West winds 5 to 15 knots becoming northwest 10 to 20 knots after midnight, then increasing to 15 to 25 knots late. A chance of showers. Waves building to 2 to 4 feet. .SUNDAY...Northwest winds 20 to 30 knots. A slight chance of showers through early afternoon. Waves building to 4 to 7 feet occasionally to 9 feet, then subsiding to 3 to 6 feet occasionally to 8 feet. .SUNDAY NIGHT...Northwest winds 15 to 25 knots becoming west 5 to 15 knots after midnight. Waves subsiding to calm to 2 feet. .MONDAY...South winds 10 to 20 knots becoming southeast 15 to 25 knots by mid afternoon. A chance of showers. Waves building to 2 to 4 feet. .MONDAY NIGHT...South winds 15 to 25 knots becoming northwest gales to 35 knots after midnight. Showers likely. Waves building to 3 to 6 feet occasionally to 8 feet. .TUESDAY...North gales to 35 knots. Rain showers likely, then a chance of rain showers. Waves building to 6 to 9 feet occasionally to 11 feet, then subsiding to 4 to 7 feet occasionally to 9 feet. .WEDNESDAY...Northwest winds 15 to 25 knots becoming west 10 to 20 knots. Waves subsiding to calm to 2 feet, then building to 1 to 3 feet. $$ LSZ265-180800- Lake Superior West of Line from Manitou Island to Marquette MI Beyond 5NM from shore- 401 PM EDT Fri Oct 17 2025 .LATE THIS AFTERNOON...South winds 15 to 25 knots. A slight chance of showers and thunderstorms. Waves 2 to 4 feet. .TONIGHT...South winds 15 to 25 knots becoming southwest 10 to 20 knots after midnight. A chance of showers and a slight chance of thunderstorms through midnight. Waves subsiding to calm to 2 feet. .SATURDAY...Southwest winds 10 to 20 knots becoming west 5 to 15 knots in the afternoon, then veering northeast late. Waves calm to 2 feet. .SATURDAY NIGHT...Northwest winds 5 to 15 knots becoming north 10 to 20 knots after midnight, then becoming northwest 15 to 25 knots late. A chance of showers. Waves building to 2 to 4 feet. .SUNDAY...Northwest gales to 35 knots. A chance of showers. Waves building to 4 to 7 feet occasionally to 9 feet. .SUNDAY NIGHT...Northwest winds 20 to 30 knots becoming west 10 to 20 knots after midnight. Waves subsiding to calm to 2 feet. .MONDAY...South winds 10 to 20 knots increasing to 20 to 30 knots by mid afternoon. Showers likely by mid afternoon. Waves calm to 2 feet. .MONDAY NIGHT...South winds 20 to 30 knots becoming west gales to 35 knots after midnight. Showers. Waves building to 2 to 4 feet. .TUESDAY...Northwest gales to 35 knots veering north. Showers, then a chance of showers. Waves building to 6 to 9 feet occasionally to 11 feet, then subsiding to 3 to 6 feet occasionally to 8 feet. .WEDNESDAY...Northwest winds 15 to 25 knots becoming west 10 to 20 knots. A chance of showers. Waves subsiding to calm to 2 feet. $$ LSZ266-180800- 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 Fri Oct 17 2025 ...GALE WATCH IN EFFECT FROM SUNDAY MORNING THROUGH SUNDAY EVENING... .LATE THIS AFTERNOON...South winds 20 to 30 knots. A slight chance of showers and thunderstorms. Waves 3 to 6 feet occasionally to 8 feet. .TONIGHT...South winds 20 to 30 knots becoming southwest 15 to 25 knots after midnight, then diminishing to 10 to 20 knots late. A slight chance of thunderstorms through midnight. A chance of showers. Waves building to 4 to 7 feet occasionally to 9 feet, then subsiding to 2 to 4 feet. .SATURDAY...Southwest winds 10 to 20 knots diminishing to 5 to 15 knots in the afternoon, then backing northeast late. A slight chance of showers by mid afternoon. Waves subsiding to calm to 2 feet. .SATURDAY NIGHT...Northeast winds 5 to 15 knots becoming north 10 to 20 knots after midnight, then increasing to 15 to 25 knots late. A chance of showers through midnight, then showers likely after midnight. Waves building to 2 to 4 feet. .SUNDAY...North gales to 35 knots backing northwest by mid afternoon. A chance of showers. Waves building to 8 to 11 feet occasionally to 14 feet. .SUNDAY NIGHT...Northwest winds 20 to 30 knots diminishing to 10 to 20 knots after midnight. A chance of showers through midnight. Waves subsiding to 3 to 5 feet occasionally to 7 feet. .MONDAY...South winds 10 to 20 knots increasing to 15 to 25 knots by mid afternoon. A chance of showers. Waves subsiding to 1 to 3 feet, then building to 2 to 4 feet. .MONDAY NIGHT...South winds 15 to 25 knots becoming west gales to 35 knots after midnight. Showers. Waves building to 4 to 7 feet occasionally to 9 feet. .TUESDAY...Northwest gales to 35 knots veering north. Showers, then a chance of showers. Waves building to 8 to 11 feet occasionally to 14 feet, then subsiding to 5 to 8 feet occasionally to 10 feet. .WEDNESDAY...Northwest winds 15 to 25 knots becoming west 10 to 20 knots. A chance of showers. Waves subsiding to 1 to 3 feet. $$ LSZ267-180800- Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off shore to the US/Canadian border- 401 PM EDT Fri Oct 17 2025 ...GALE WATCH IN EFFECT FROM SUNDAY MORNING THROUGH SUNDAY EVENING... .LATE THIS AFTERNOON...South winds 20 to 30 knots. Waves 3 to 5 feet occasionally to 7 feet. .TONIGHT...South winds 20 to 30 knots diminishing to 15 to 25 knots after midnight, then becoming southwest 10 to 20 knots late. Showers likely and a slight chance of thunderstorms through midnight, then a chance of showers after midnight. Waves building to 3 to 6 feet occasionally to 8 feet, then subsiding to 1 to 3 feet. .SATURDAY...Southwest winds 10 to 20 knots diminishing to 5 to 15 knots in the afternoon, then veering north late. A slight chance of showers. Waves subsiding to calm to 2 feet. .SATURDAY NIGHT...East winds 5 to 15 knots backing northeast after midnight, then becoming north 10 to 20 knots late. A chance of showers through midnight, then showers likely after midnight. Waves building to 1 to 3 feet. .SUNDAY...North winds 20 to 30 knots becoming northwest gales to 35 knots by mid afternoon. Showers likely through early afternoon, then a chance of showers by mid afternoon. Waves building to 8 to 12 feet occasionally to 15 feet. .SUNDAY NIGHT...Northwest winds 20 to 30 knots diminishing to 15 to 25 knots after midnight. A chance of showers through midnight. Waves subsiding to 3 to 5 feet occasionally to 7 feet. .MONDAY...Southwest winds 10 to 20 knots becoming south 15 to 25 knots by mid afternoon. A chance of showers. Waves subsiding to 1 to 3 feet. .MONDAY NIGHT...Southeast winds 20 to 30 knots. Showers. Waves building to 3 to 6 feet occasionally to 8 feet. .TUESDAY...Northwest gales to 35 knots veering north. Showers. Waves building to 7 to 10 feet occasionally to 13 feet, then subsiding to 5 to 8 feet occasionally to 10 feet. .WEDNESDAY...Northwest winds 15 to 25 knots diminishing to 10 to 20 knots. A chance of showers. Waves subsiding to 1 to 3 feet. $$ LSZ261-180200- MAFOR 1721/ Superior West 11420 12530 11520 12510 12610. Waves 1 to 3 feet building to 3 to 5 feet, then subsiding to 2 to 4 feet tonight. Waves 1 to 3 feet Saturday. Superior North Central 11420 11430 11530 12520 13610. A chance of showers this evening. Waves 2 to 4 feet building to 3 to 5 feet tonight. Waves 3 to 5 feet subsiding to 2 to 3 feet Saturday. Superior South Central 12430 11530 13510 11500 11700. A chance of showers this evening. Waves 2 to 4 feet subsiding to 1 to 3 feet tonight. Waves 2 feet or less Saturday. Superior East 11440 12446 11520 11510 12500 11600. Waves 3 to 6 feet tonight. Waves 1 to 3 feet Saturday. $$ 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