917 FZUS61 KBUF 182002 GLFLO Open Lake Forecast for Lake Ontario National Weather Service Buffalo NY 402 PM EDT Mon May 18 2026 For waters beyond five nautical miles of shore on Lake Ontario 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...An area of low pressure developing over the Central Plains today will weaken from 29.4 inches to 29.6 inches as it tracks northeast to the Upper Great Lakes tonight into Tuesday morning, then to central Quebec Wednesday while strengthening to 29.4 inches. A cold front attendant to this low will cross the Lake late Tuesday night into Wednesday morning. A large 30.4 inch high will then build across the entire Great Lakes region Wednesday night through Thursday. High pressure will move to the east and weaken to 30.1 inches Friday. A 29.9 inch low will track across the Ohio Valley and near the lake Saturday. LOZ062-190300- Lake Ontario open waters from the Niagara River to Hamlin Beach- 402 PM EDT Mon May 18 2026 .TONIGHT...Southwest winds 10 to 15 knots. A chance of showers after midnight. Waves 1 to 3 feet. .TUESDAY...Southwest winds 10 to 15 knots increasing to 15 to 20 knots. Waves 1 to 3 feet building to 3 to 5 feet. .TUESDAY NIGHT...Southwest winds 15 to 20 knots becoming west. Showers with a chance of thunderstorms in the evening, then showers likely overnight. Waves 3 to 5 feet. .WEDNESDAY...West winds 15 to 20 knots. Showers likely in the morning. Waves 2 to 4 feet subsiding to 1 to 3 feet. .WEDNESDAY NIGHT...Northwest winds 10 to 15 knots becoming north. Waves 1 to 3 feet. .THURSDAY...Northeast winds 10 knots or less becoming east. Waves 2 feet or less. .FRIDAY...East winds 10 to 15 knots increasing to 15 to 20 knots. Showers likely Friday night. Waves 2 feet or less building to 2 to 4 feet. .SATURDAY...East winds 15 to 25 knots diminishing to 10 to 15 knots. Showers likely during the day, then a chance of showers Saturday night. Waves 3 to 6 feet subsiding to 2 to 4 feet. Winds and waves higher in and near thunderstorms. $$ LOZ063>065-190300- Lake Ontario open waters from Hamlin Beach to the Saint Lawrence River- 402 PM EDT Mon May 18 2026 .TONIGHT...South winds 5 to 10 knots becoming southwest. A chance of showers. Waves 2 feet or less. .TUESDAY...Southwest winds 10 to 15 knots. Waves 1 to 3 feet building to 2 to 4 feet. .TUESDAY NIGHT...Southwest winds 15 to 20 knots becoming west. Showers likely with a chance of thunderstorms in the evening, then showers likely overnight. Waves 2 to 4 feet building to 3 to 5 feet. .WEDNESDAY...West winds 15 to 25 knots. A chance of showers in the morning. Waves 3 to 6 feet building to 4 to 7 feet. Waves occasionally around 9 feet. .WEDNESDAY NIGHT...West winds 15 to 20 knots becoming north 10 to 15 knots. Waves 4 to 7 feet subsiding to 2 to 4 feet. Waves occasionally around 9 feet. .THURSDAY...North winds 5 to 15 knots becoming east less than 10 knots. Waves 1 to 3 feet subsiding to 1 foot or less. .FRIDAY...East winds 5 to 15 knots. A chance of showers Friday night. Waves 1 to 3 feet. .SATURDAY...Southeast winds 15 to 20 knots diminishing to 10 to 15 knots. Showers likely. Waves 2 to 4 feet building to 3 to 5 feet, then subsiding to 1 to 3 feet. Winds and waves higher in and near thunderstorms. $$ LOZ061-190300- MAFOR 1821/ ONTARIO WEST 1/2 15510 12520. Waves 1 to 3 feet tonight. Waves 1 to 3 feet building to 3 to 5 feet Tuesday. ONTARIO EAST 1/2 12400 14500 12510. Waves 2 feet or less tonight. Waves 1 to 3 feet Tuesday. $$  981 FZUS61 KBUF 182003 GLFSL Forecast for the Saint Lawrence River including the Thousand Islands Region National Weather Service Buffalo NY 403 PM EDT Mon May 18 2026 SLZ022-024-190300- Saint Lawrence River from Cape Vincent to Saint Regis 403 PM EDT Mon May 18 2026 .TONIGHT...Southwest winds 5 to 10 knots. A chance of showers late. .TUESDAY...Southwest winds 5 to 15 knots. A chance of showers early. .TUESDAY NIGHT...Southwest winds 10 to 15 knots. Showers likely. .WEDNESDAY...Southwest winds 10 to 15 knots becoming west. A chance of showers in the morning. .WEDNESDAY NIGHT...Northwest winds 5 to 15 knots becoming north. Mainly clear in the evening, then becoming partly cloudy. .THURSDAY...North winds 5 to 10 knots becoming light and variable. Mainly clear. .FRIDAY...Light and variable winds. A chance of showers Friday night. .SATURDAY...East winds 10 knots or less becoming southeast. A chance of showers. $$  908 FZUS63 KMQT 182002 GLFLS Open Lake Forecast for Lake Superior National Weather Service Marquette MI 401 PM EDT Mon May 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... Low pressure will weaken to 29.9 inches over Lake Superior tonight. Another low will follow, reaching Lake Superior by Tuesday morning at 29.6 inches. Afterwards, a 30.2 inch high over the Northern Plains builds to 30.4 inches Tuesday night into Wednesday as it tracks eastward into the Upper Great Lakes. The high pressure shifts east on Thursday while leaving lingering ridging of at least 30.1 inches over Lake Superior into Friday. A 29.9 inch low lifts into the Great Lakes from the Southern Plains for Saturday, but 30.1 inch ridging persists over Lake Superior. LSZ162-190800- Lake Superior west of a line from Saxon Harbor WI to Grand Portage MN beyond 5NM- 401 PM EDT Mon May 18 2026 /301 PM CDT Mon May 18 2026/ .LATE THIS AFTERNOON...Northeast winds 5 to 15 knots. Patchy fog. Waves 1 to 3 feet. .TONIGHT...Northeast winds 10 to 20 knots increasing to 15 to 25 knots after midnight. Patchy fog. A chance of showers and thunderstorms through midnight. Rain showers after midnight. Waves building to 3 to 6 feet occasionally to 8 feet. .TUESDAY...West winds 10 to 20 knots. Patchy fog through early afternoon. A chance of rain showers through early afternoon. Waves subsiding to 1 to 3 feet. .TUESDAY NIGHT...Northwest winds 10 to 20 knots diminishing to 5 to 15 knots after midnight. Waves subsiding to calm to 2 feet. .WEDNESDAY...Northwest winds 5 to 15 knots backing south by mid afternoon. Waves calm to 2 feet. .WEDNESDAY NIGHT...Southeast winds 5 to 15 knots becoming south less than 10 knots after midnight. Waves calm to 2 feet. .THURSDAY...South winds 5 to 15 knots backing east by mid afternoon. Waves calm to 2 feet. .THURSDAY NIGHT...East winds 5 to 15 knots. Waves building to 1 to 3 feet, then subsiding to calm to 2 feet. .FRIDAY...East winds 10 to 20 knots backing northeast. A chance of rain showers. Waves building to 1 to 3 feet, then subsiding to calm to 2 feet. .SATURDAY...Northeast winds 10 to 20 knots diminishing to 5 to 15 knots. A chance of rain showers. Waves calm to 2 feet. $$ LSZ263-190800- Lake Superior from Saxon Harbor WI to Upper Entrance to Portage Canal MI 5NM off shore to the US/Canadian border including Isle Royale National Park- 401 PM EDT Mon May 18 2026 .LATE THIS AFTERNOON...Northeast winds 10 to 20 knots. Patchy fog. Waves 1 to 3 feet. .TONIGHT...Northeast winds 15 to 25 knots. Patchy fog. A chance of rain showers through midnight. A chance of thunderstorms. Rain showers after midnight. Waves building to 3 to 6 feet occasionally to 8 feet. .TUESDAY...North winds 10 to 20 knots backing west in the afternoon. Patchy fog through early afternoon. A chance of rain showers through early afternoon. Waves subsiding to 2 to 4 feet. .TUESDAY NIGHT...Northwest winds 10 to 20 knots diminishing to 5 to 15 knots after midnight. Waves subsiding to calm to 2 feet. .WEDNESDAY...Northwest winds 5 to 15 knots becoming south 10 to 20 knots by mid afternoon. Waves building to 1 to 3 feet. .WEDNESDAY NIGHT...South winds 5 to 15 knots. Waves subsiding to calm to 2 feet. .THURSDAY...South winds 5 to 15 knots backing east by mid afternoon. Waves calm to 2 feet. .THURSDAY NIGHT...Southeast winds 5 to 15 knots veering south after midnight. Waves building to 1 to 3 feet. .FRIDAY...East winds 10 to 20 knots. Waves subsiding to calm to 2 feet, then building to 1 to 3 feet. .SATURDAY...East winds 5 to 15 knots. A chance of rain showers. Waves subsiding to calm to 2 feet. $$ LSZ264-190800- Lake Superior from Upper Entrance to Portage Canal to Manitou Island MI 5NM off shore to the US/Canadian Border- 401 PM EDT Mon May 18 2026 ...DENSE FOG ADVISORY IN EFFECT UNTIL 11 AM EDT TUESDAY... .LATE THIS AFTERNOON...Northeast winds 5 to 15 knots. Patchy fog. Waves 2 to 4 feet subsiding to 1 to 3 feet. .TONIGHT...Northeast winds 15 to 25 knots veering east late. Patchy dense fog. A chance of rain showers through midnight. A chance of thunderstorms. Rain showers after midnight. Waves building to 3 to 6 feet occasionally to 8 feet. .TUESDAY...North winds 15 to 25 knots backing northwest in the afternoon. Patchy fog through early afternoon. A chance of rain showers through early afternoon. Waves subsiding to 2 to 4 feet. .TUESDAY NIGHT...Northwest winds 10 to 20 knots. Waves building to 3 to 5 feet occasionally to 7 feet, then subsiding to 1 to 3 feet. .WEDNESDAY...Northwest winds 5 to 15 knots backing southwest by mid afternoon. Waves subsiding to calm to 2 feet. .WEDNESDAY NIGHT...South winds 5 to 15 knots. Waves calm to 2 feet. .THURSDAY...South winds 5 to 15 knots backing southeast by mid afternoon. Waves building to 1 to 3 feet. .THURSDAY NIGHT...Southeast winds 5 to 15 knots veering south after midnight. Waves building to 2 to 4 feet, then subsiding to 1 to 3 feet. .FRIDAY...East winds 5 to 15 knots. Waves 1 to 3 feet. .SATURDAY...East winds 5 to 15 knots veering southeast. Waves subsiding to calm to 2 feet. $$ LSZ265-190800- Lake Superior West of Line from Manitou Island to Marquette MI Beyond 5NM from shore- 401 PM EDT Mon May 18 2026 ...DENSE FOG ADVISORY IN EFFECT UNTIL 11 AM EDT TUESDAY... .LATE THIS AFTERNOON...North winds 10 to 20 knots. Patchy fog. Waves calm to 2 feet. .TONIGHT...Northeast winds 10 to 20 knots becoming east 5 to 15 knots after midnight, then increasing to 10 to 20 knots late. Patchy fog through midnight. Areas of dense fog after midnight. A chance of rain showers through midnight. A chance of thunderstorms. Rain showers after midnight. Waves building to 1 to 3 feet. .TUESDAY...West winds 15 to 25 knots increasing to 20 to 30 knots in the afternoon, then veering northwest late. Patchy fog through early afternoon. A chance of rain showers through early afternoon. Waves building to 3 to 6 feet occasionally to 8 feet. .TUESDAY NIGHT...Northwest winds 15 to 25 knots. Waves building to 3 to 6 feet occasionally to 8 feet. .WEDNESDAY...Northwest winds 10 to 20 knots becoming north 5 to 15 knots by mid afternoon. Waves subsiding to calm to 2 feet. .WEDNESDAY NIGHT...South winds 5 to 15 knots. Waves calm to 2 feet. .THURSDAY...South winds 10 to 20 knots becoming southeast 15 to 25 knots by mid afternoon. Waves building to 2 to 4 feet. .THURSDAY NIGHT...Southeast winds 10 to 20 knots becoming south 5 to 15 knots after midnight. Waves subsiding to 1 to 3 feet. .FRIDAY...East winds 10 to 20 knots. Waves building to 2 to 4 feet, then subsiding to 1 to 3 feet. .SATURDAY...East winds 10 to 20 knots veering southeast. Waves subsiding to calm to 2 feet. $$ 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- 401 PM EDT Mon May 18 2026 ...DENSE FOG ADVISORY IN EFFECT UNTIL 11 AM EDT TUESDAY... .LATE THIS AFTERNOON...North winds 10 to 20 knots. Patchy fog. Waves 1 to 3 feet. .TONIGHT...Northeast winds 10 to 20 knots veering southeast late. Areas of dense fog. A chance of rain showers through midnight. A chance of thunderstorms. Rain showers likely after midnight. Waves building to 3 to 5 feet occasionally to 7 feet, then subsiding to 2 to 4 feet. .TUESDAY...South winds 15 to 25 knots becoming northwest 20 to 30 knots in the afternoon. Patchy fog through early afternoon. A chance of rain showers and a slight chance of thunderstorms through early afternoon. Waves building to 5 to 8 feet occasionally to 10 feet. .TUESDAY NIGHT...Northwest winds 20 to 30 knots. Waves subsiding to 4 to 8 feet occasionally to 10 feet. .WEDNESDAY...Northwest winds 10 to 20 knots diminishing to 5 to 15 knots by mid afternoon. Waves subsiding to 1 to 3 feet. .WEDNESDAY NIGHT...West winds 5 to 15 knots backing south after midnight. Waves subsiding to calm to 2 feet. .THURSDAY...South winds 5 to 15 knots becoming southeast 10 to 20 knots by mid afternoon. Waves building to 1 to 3 feet. .THURSDAY NIGHT...Southeast winds 10 to 20 knots veering south after midnight. Waves building to 2 to 4 feet, then subsiding to 1 to 3 feet. .FRIDAY...East winds 10 to 20 knots. Waves 1 to 3 feet. .SATURDAY...East winds 10 to 20 knots veering southeast. Waves subsiding to calm to 2 feet. $$ LSZ267-190800- Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off shore to the US/Canadian border- 401 PM EDT Mon May 18 2026 ...DENSE FOG ADVISORY IN EFFECT UNTIL 2 PM EDT TUESDAY... .LATE THIS AFTERNOON...Northeast winds 5 to 15 knots. Areas of dense fog. Waves calm to 2 feet. .TONIGHT...East winds 10 to 20 knots becoming southeast 15 to 25 knots late. Areas of dense fog. A chance of showers and thunderstorms. Waves building to 1 to 3 feet. .TUESDAY...South winds 15 to 25 knots becoming west 20 to 30 knots in the afternoon, then becoming northwest to 30 knots with a few gale force gusts to 35 knots possible late. Areas of dense fog through early afternoon. Patchy fog by mid afternoon. A slight chance of thunderstorms through early afternoon. A chance of rain showers. Waves building to 5 to 8 feet occasionally to 10 feet. .TUESDAY NIGHT...Northwest winds 20 to 30 knots. Waves subsiding to 4 to 8 feet occasionally to 10 feet. .WEDNESDAY...Northwest winds 15 to 25 knots diminishing to 10 to 20 knots by mid afternoon. Waves subsiding to 2 to 4 feet. .WEDNESDAY NIGHT...Northwest winds 5 to 15 knots backing south after midnight. Waves subsiding to calm to 2 feet. .THURSDAY...South winds 5 to 15 knots backing east by mid afternoon. Waves calm to 2 feet. .THURSDAY NIGHT...Southeast winds 5 to 15 knots. Waves calm to 2 feet. .FRIDAY...East winds 5 to 15 knots increasing to 10 to 20 knots. Waves building to 1 to 3 feet, then subsiding to calm to 2 feet. .SATURDAY...East winds 10 to 20 knots veering southeast. Waves calm to 2 feet. $$ LSZ261-190200- MAFOR 1821/ Superior West 11110 11230 12136 11836 11720 11610 11620. A chance of thunderstorms tonight. Waves 2 to 4 feet building to 3 to 6 feet tonight. Waves 3 to 6 feet Tuesday. Superior North Central 11120 12130 11236 19234 11136 19134 11830 12730. Waves 2 to 4 feet building to 3 to 6 feet tonight. Waves 3 to 6 feet Tuesday. Superior South Central 11810 12110 11216 19214 11316 19314 11534 11640 11740. Waves 1 to 3 feet tonight. Waves 2 to 4 feet building to 4 to 6 feet Tuesday. Superior East 11804 11104 11224 11234 11326 19324 11424 11630 11640. Waves 1 to 3 feet building to 3 to 5 feet tonight. Waves 3 to 6 feet building to 5 to 7 feet Tuesday. $$ 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