697 FZUS61 KBUF 181402 GLFLO Open Lake Forecast for Lake Ontario National Weather Service Buffalo NY 1002 AM 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 will develop over the Central Plains today. The low 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. LOZ062-182100- Lake Ontario open waters from the Niagara River to Hamlin Beach- 1002 AM EDT Mon May 18 2026 .THIS AFTERNOON...Southwest winds 10 to 15 knots increasing to 15 to 20 knots. Waves 1 to 3 feet building to 2 to 4 feet. .TONIGHT...Southwest winds 15 to 20 knots diminishing to 10 to 15 knots. A chance of showers after midnight. Waves 2 to 4 feet subsiding to 1 to 3 feet. .TUESDAY...Southwest winds 15 to 25 knots. A chance of showers in the morning. Waves 1 to 3 feet building to 3 to 6 feet. .TUESDAY NIGHT...Southwest winds 15 to 25 knots becoming west. Showers with a chance of thunderstorms in the evening, then showers overnight. Waves 3 to 6 feet. .WEDNESDAY...West winds 15 to 20 knots becoming northwest 10 to 15 knots. A chance of showers during the day. Waves 2 to 4 feet subsiding to 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. A chance of showers Friday night. Waves 2 feet or less building to 2 to 4 feet. Winds and waves higher in and near thunderstorms. $$ LOZ063>065-182100- Lake Ontario open waters from Hamlin Beach to the Saint Lawrence River- 1002 AM EDT Mon May 18 2026 .THIS AFTERNOON...Southwest winds 5 to 15 knots becoming south. Waves 2 feet or less. .TONIGHT...South winds 5 to 10 knots becoming southwest. A chance of showers from late evening on. Waves 2 feet or less. .TUESDAY...Southwest winds 10 to 15 knots. Waves 1 to 3 feet building to 2 to 4 feet. .TUESDAY NIGHT...Southwest winds 15 to 20 knots becoming west. Showers with a chance of thunderstorms. Waves 2 to 4 feet building to 3 to 5 feet. .WEDNESDAY...West winds 15 to 25 knots becoming northwest. Showers likely during the day. Waves 3 to 5 feet building to 4 to 7 feet, then subsiding to 3 to 5 feet. Waves occasionally around 9 feet. .THURSDAY...North winds 5 to 15 knots becoming east less than 10 knots. Waves 1 to 3 feet subsiding to 1 foot or less. .FRIDAY...East winds 5 to 15 knots becoming southeast. A chance of showers Friday night. Waves 1 to 3 feet. Winds and waves higher in and near thunderstorms. $$ LOZ061-182100- MAFOR 1815/ ONTARIO WEST 1/2 11510 11520 14510 11510 11520. Waves 1 to 3 feet building to 2 to 4 feet this afternoon. Waves 2 to 4 feet subsiding to 1 to 3 feet tonight. Waves 1 to 3 feet Tuesday morning. ONTARIO EAST 1/2 11510 11500 13400 13500. Waves 2 feet or less. $$  733 FZUS61 KBUF 181403 GLFSL Forecast for the Saint Lawrence River including the Thousand Islands Region National Weather Service Buffalo NY 1003 AM EDT Mon May 18 2026 SLZ022-024-182100- Saint Lawrence River from Cape Vincent to Saint Regis 1003 AM EDT Mon May 18 2026 .THIS AFTERNOON...South winds 5 to 10 knots becoming southwest. Becoming mostly sunny. .TONIGHT...Southwest winds 5 to 10 knots. A chance of showers after midnight. .TUESDAY...Southwest winds 5 to 15 knots increasing to 15 to 20 knots. A chance of showers in the morning. .TUESDAY NIGHT...Southwest winds 15 to 20 knots diminishing to 10 to 15 knots. Showers likely with a chance of thunderstorms in the evening, then showers likely overnight. .WEDNESDAY...West winds 5 to 15 knots becoming north. A chance of showers during the day. .THURSDAY...North winds 5 to 10 knots becoming light and variable. Mainly clear. .FRIDAY...Light and variable winds. A chance of showers Friday night. Winds and waves higher in and near thunderstorms. $$  655 FZUS63 KMQT 181402 GLFLS Open Lake Forecast for Lake Superior National Weather Service Marquette MI 1001 AM 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 over the lake today with another low pressure following it, 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 traverses eastwards 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 maintains over Lake Superior. LSZ162-182000- Lake Superior west of a line from Saxon Harbor WI to Grand Portage MN beyond 5NM- 1001 AM EDT Mon May 18 2026 /901 AM CDT Mon May 18 2026/ .REST OF TODAY...North winds 5 to 15 knots veering northeast in the afternoon. Patchy fog. A slight chance of rain showers by mid afternoon. Waves 2 to 4 feet subsiding to 1 to 3 feet. .TONIGHT...Northeast winds 15 to 25 knots. Patchy fog. A chance of rain showers through midnight. A slight chance of thunderstorms. Rain showers after midnight. Waves building to 4 to 7 feet occasionally to 9 feet. .TUESDAY...North winds 10 to 20 knots backing west in the afternoon. A chance of rain showers through early afternoon. Waves subsiding to 1 to 3 feet. .TUESDAY NIGHT...Northwest winds 5 to 15 knots. Waves subsiding to calm to 2 feet. .WEDNESDAY...Southwest winds 5 to 15 knots backing south by mid afternoon. Waves calm to 2 feet. .WEDNESDAY NIGHT...Southeast winds 5 to 15 knots veering south after midnight. Waves calm to 2 feet. .THURSDAY...East winds 5 to 15 knots. Waves building to 1 to 3 feet, then subsiding to calm to 2 feet. .FRIDAY...East winds 5 to 15 knots backing northeast. Waves building to 1 to 3 feet, then subsiding to calm to 2 feet. $$ LSZ263-182000- Lake Superior from Saxon Harbor WI to Upper Entrance to Portage Canal MI 5NM off shore to the US/Canadian border including Isle Royale National Park- 1001 AM EDT Mon May 18 2026 .REST OF TODAY...North winds 5 to 15 knots becoming northeast 10 to 20 knots late. Patchy fog. A slight chance of rain showers by mid afternoon. Waves 3 to 5 feet occasionally to 7 feet subsiding to 1 to 3 feet. .TONIGHT...Northeast winds 15 to 25 knots. Patchy fog. A chance of rain showers through midnight. A slight chance of thunderstorms. Rain showers after midnight. Waves building to 5 to 8 feet occasionally to 10 feet. .TUESDAY...North winds 15 to 25 knots becoming west 10 to 20 knots in the afternoon. A chance of rain showers through early afternoon. Waves subsiding to 2 to 4 feet. .TUESDAY NIGHT...Northwest winds 10 to 20 knots diminishing to 5 to 15 knots after midnight. Waves subsiding to calm to 2 feet. .WEDNESDAY...Northwest winds 5 to 15 knots backing southwest by mid afternoon. Waves building to 1 to 3 feet. .WEDNESDAY NIGHT...South winds 5 to 15 knots. Waves subsiding to calm to 2 feet. .THURSDAY...South winds 5 to 15 knots increasing to 10 to 20 knots. Waves building to 1 to 3 feet. .FRIDAY...East winds 5 to 15 knots. Waves subsiding to calm to 2 feet, then building to 1 to 3 feet. $$ LSZ264-182000- Lake Superior from Upper Entrance to Portage Canal to Manitou Island MI 5NM off shore to the US/Canadian Border- 1001 AM EDT Mon May 18 2026 ...DENSE FOG ADVISORY IN EFFECT UNTIL 5 PM EDT THIS AFTERNOON... .REST OF TODAY...Northeast winds 5 to 15 knots backing north in the afternoon, then increasing to 10 to 20 knots late. Patchy dense fog. A slight chance of rain showers by mid afternoon. Waves 3 to 5 feet occasionally to 7 feet subsiding to 2 to 4 feet. .TONIGHT...Northeast winds 15 to 25 knots. Patchy fog. A chance of rain showers through midnight. A slight chance of thunderstorms. Rain showers after midnight. Waves building to 4 to 7 feet occasionally to 9 feet. .TUESDAY...North winds 15 to 25 knots backing northwest in the afternoon. Patchy fog through early afternoon. Rain showers likely through early afternoon. Waves building to 5 to 8 feet occasionally to 10 feet, then subsiding to 3 to 6 feet occasionally to 8 feet. .TUESDAY NIGHT...Northwest winds 15 to 25 knots diminishing to 10 to 20 knots after midnight. Waves subsiding to 1 to 3 feet. .WEDNESDAY...Northwest winds 10 to 20 knots becoming southwest 5 to 15 knots by mid afternoon. Waves subsiding to calm to 2 feet. .WEDNESDAY NIGHT...Southwest winds 5 to 15 knots backing south after midnight. Waves calm to 2 feet. .THURSDAY...South winds 5 to 15 knots increasing to 10 to 20 knots. Waves building to 2 to 4 feet, then subsiding to 1 to 3 feet. .FRIDAY...Southeast winds 5 to 15 knots. Waves 1 to 3 feet. $$ LSZ265-182000- Lake Superior West of Line from Manitou Island to Marquette MI Beyond 5NM from shore- 1001 AM EDT Mon May 18 2026 ...DENSE FOG ADVISORY IN EFFECT UNTIL 5 PM EDT THIS AFTERNOON... .REST OF TODAY...South winds 10 to 20 knots veering west in the afternoon, then veering north late. Patchy dense fog. A chance of showers. Waves 2 to 4 feet subsiding to calm to 2 feet. .TONIGHT...North winds 10 to 20 knots veering east late. Areas of dense fog through midnight. Patchy fog after midnight. A chance of rain showers through midnight. A slight chance of thunderstorms. Rain showers after midnight. Waves building to 2 to 4 feet. .TUESDAY...Northwest winds 15 to 25 knots increasing to 20 to 30 knots in the afternoon. Patchy fog through early afternoon. Rain showers likely and a slight chance of thunderstorms through early afternoon. Waves building to 4 to 7 feet occasionally to 9 feet. .TUESDAY NIGHT...Northwest winds 15 to 25 knots. Waves subsiding to 3 to 5 feet occasionally to 7 feet. .WEDNESDAY...Northwest winds 10 to 20 knots becoming south 5 to 15 knots by mid afternoon. Waves subsiding to calm to 2 feet. .WEDNESDAY NIGHT...South winds 5 to 15 knots increasing to 10 to 20 knots after midnight. Waves calm to 2 feet. .THURSDAY...Southeast winds 10 to 20 knots veering south. Waves building to 2 to 4 feet, then subsiding to 1 to 3 feet. .FRIDAY...Southeast winds 10 to 20 knots. Waves building to 2 to 4 feet, then subsiding to 1 to 3 feet. $$ LSZ266-182000- 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- 1001 AM EDT Mon May 18 2026 ...DENSE FOG ADVISORY IN EFFECT UNTIL 5 PM EDT THIS AFTERNOON... .REST OF TODAY...South winds 10 to 20 knots veering southwest in the afternoon, then veering north late. Patchy dense fog. A slight chance of showers. Waves 3 to 5 feet occasionally to 7 feet subsiding to 2 to 4 feet. .TONIGHT...Northeast winds 15 to 25 knots veering east after midnight. 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 6 feet occasionally to 8 feet. .TUESDAY...South winds 15 to 25 knots becoming northwest 20 to 30 knots in the afternoon, then increasing to 30 knots with a few gale force gusts to 35 knots possible late. Areas of dense fog through early afternoon. A slight chance of thunderstorms through early afternoon. A chance of rain showers. Waves building to 7 to 10 feet occasionally to 13 feet. .TUESDAY NIGHT...Northwest winds 20 to 30 knots. Waves subsiding to 4 to 7 feet occasionally to 9 feet. .WEDNESDAY...Northwest winds 15 to 25 knots becoming west 5 to 15 knots by mid afternoon. Waves subsiding to 1 to 3 feet. .WEDNESDAY NIGHT...Southwest winds 5 to 15 knots backing south after midnight. Waves subsiding to calm to 2 feet. .THURSDAY...South winds 10 to 20 knots. Waves building to 2 to 4 feet, then subsiding to 1 to 3 feet. .FRIDAY...Southeast winds 15 to 25 knots diminishing to 10 to 20 knots. Waves 1 to 3 feet. $$ LSZ267-182000- Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off shore to the US/Canadian border- 1001 AM EDT Mon May 18 2026 ...DENSE FOG ADVISORY IN EFFECT UNTIL 8 PM EDT THIS EVENING... .REST OF TODAY...South winds 10 to 20 knots veering southwest in the afternoon, then becoming north 5 to 15 knots late. Areas of dense fog. A slight chance of showers. Waves 2 to 4 feet subsiding to calm to 2 feet. .TONIGHT...East winds 5 to 15 knots becoming southeast 10 to 20 knots late. Areas of dense fog. A chance of showers and thunderstorms. Waves building to 2 to 4 feet. .TUESDAY...South winds 15 to 25 knots becoming west 20 to 30 knots in the afternoon, then increasing to 30 knots with a few gale force gusts to 35 knots possible late. Areas of dense fog through early afternoon. A slight chance of thunderstorms through early afternoon. A chance of rain showers. Waves building to 8 to 11 feet occasionally to 14 feet. .TUESDAY NIGHT...Northwest gales to 35 knots diminishing to 20 to 30 knots after midnight. Waves subsiding to 4 to 7 feet occasionally to 9 feet. .WEDNESDAY...Northwest winds 20 to 30 knots diminishing to 10 to 20 knots by mid afternoon. Waves subsiding to 2 to 4 feet. .WEDNESDAY NIGHT...West winds 5 to 15 knots backing south after midnight. Waves subsiding to calm to 2 feet. .THURSDAY...East winds 5 to 15 knots veering southeast. Waves calm to 2 feet. .FRIDAY...Southeast winds 10 to 20 knots. Waves building to 1 to 3 feet, then subsiding to calm to 2 feet. $$ LSZ261-182000- MAFOR 1815/ Superior West 12110 11120 11130 11136 11146 11136 11820. Waves 2 to 4 feet this afternoon. Waves 2 to 3 feet building to 5 to 7 feet tonight. Waves 5 to 8 feet Tuesday morning. Superior North Central 12810 19814 11820 12130 12136 11836. Waves 3 to 5 feet this afternoon. Waves 3 to 6 feet building to 4 to 7 feet tonight. Waves 4 to 7 feet Tuesday morning. Superior South Central 11420 19424 11710 19714 11820 11810 11114 11216 11326 19324 11420. A chance of thunderstorms overnight and Tuesday morning. Waves 2 to 4 feet this afternoon. Waves 1 to 3 feet tonight. Waves 2 to 4 feet Tuesday morning. Superior East 11424 11614 11804 11104 11224 11234 11336 19334 11426 19424. A chance of thunderstorms overnight and Tuesday morning. Waves 2 to 4 feet this afternoon. Waves 1 to 2 feet building to 3 to 5 feet tonight. Waves 3 to 5 feet Tuesday morning. $$ 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  590 FZUS63 KMKX 181414 GLFLM OPEN LAKE FORECAST for Lake Michigan National Weather Service Milwaukee/Sullivan WI 914 AM CDT Mon May 18 2026 FOR WATERS BEYOND FIVE NAUTICAL MILES OF SHORE ON Lake Michigan. Waves are provided as a range of significant wave heights, which is the average of the highest 1/3 of the wave, along with the average height of the highest 10% of the waves which will occasionally be encountered. .SYNOPSIS... Areas of dense fog over the lake this morning with breezy south to southwest winds today. These winds will increase slightly across the lake late tonight and remain breezy ahead of the cold frontal passage expected Tuesday afternoon as the low pressure system around 29.6 inches swings northeast of the Lake into Ontario. High pressure around 30.4 inches will push in with light and variable winds taking hold from late Wednesday into Thursday. LMZ261-362-364-366-563-565-567-868-182115- Lake Michigan from Seul Choix Point to Rock Island Passage 5 NM offshore to Mid Lake- Lake Michigan South of a line from Seul Choix Point to the Mackinac Bridge and north of a line from Charlevoix MI to South Fox Island 5 NM offshore- Lake Michigan from Charlevoix to Point Betsie MI 5 NM offshore to Mid Lake- Lake Michigan from Point Betsie to Manistee MI 5 NM offshore to Mid Lake- Lake Michigan from Rock Island Passage to Sturgeon Bay WI- Lake Michigan from Sturgeon Bay to Two Rivers WI 5 NM offshore to Mid Lake- Lake Michigan from Two Rivers to Sheboygan WI 5 NM offshore to Mid Lake- Lake Michigan from Pentwater to Manistee MI 5 NM offshore to Mid Lake- 914 AM CDT Mon May 18 2026 SHEBOYGAN WI TO PENTWATER MI NORTH... .REST OF TODAY...South winds to 30 kt. Patchy fog. Chance of showers and slight chance of thunderstorms late this morning, then slight chance of showers and thunderstorms this afternoon. Waves 4 to 6 ft occasionally to 8 ft. .TONIGHT...South winds 15 to 25 kt increasing to 30 kt. Patchy dense fog in the evening, then areas of dense fog overnight. Chance of rain showers and thunderstorms overnight. Waves 4 to 7 ft occasionally to 9 ft building to 5 to 8 ft occasionally to 10 ft. .TUESDAY...South winds to 30 kt veering to west. Chance of rain showers. Waves 7 to 10 ft occasionally to 13 ft. .TUESDAY NIGHT...Northwest winds 15 to 25 kt. Waves 4 to 7 ft occasionally to 9 ft subsiding to 3 to 5 ft. .WEDNESDAY...North winds 15 to 25 kt diminishing to 10 to 20 kt. Waves 2 to 4 ft. .WEDNESDAY NIGHT...Northeast winds 10 to 20 kt diminishing to 5 to 10 kt. Waves 1 to 3 ft. .THURSDAY...East winds 5 to 10 kt becoming northeast 10 to 20 kt. Waves 1 to 2 ft. .FRIDAY...Southeast winds 10 to 20 kt becoming east. Waves 1 to 3 ft. $$ LMZ080-669-671-673-675-777-779-870-872-874-876-878-182115- Lake Michigan from Michigan City IN to St. Joseph MI 5 NM offshore to Mid Lake- Lake Michigan from Sheboygan to Port Washington WI 5 NM offshore to Mid Lake- Lake Michigan from Port Washington to North Point Light WI 5 NM offshore to Mid Lake- Lake Michigan from North Point Light to Wind Point WI 5 NM offshore to Mid Lake- Lake Michigan from Wind Point WI to Winthrop Harbor IL 5 NM offshore to Mid Lake- Lake Michigan from Winthrop Harbor to Wilmette Harbor IL 5 NM offshore to Mid Lake- Lake Michigan from Wilmette Harbor IL to Michigan City IN 5 NM offshore to Mid Lake- Lake Michigan from Whitehall to Pentwater MI 5 NM offshore to Mid Lake- Lake Michigan from Grand Haven to Whitehall MI 5 NM offshore to Mid Lake- Lake Michigan from Holland to Grand Haven MI 5 NM offshore to Mid Lake- Lake Michigan from South Haven to Holland MI 5 NM offshore to Mid Lake- Lake Michigan from St. Joseph to South Haven MI 5 NM offshore to Mid Lake- 914 AM CDT Mon May 18 2026 SHEBOYGAN WI TO PENTWATER MI SOUTH... .REST OF TODAY...South winds 15 to 25kt. Chance of showers and slight chance of thunderstorms late this morning, then slight chance of showers and thunderstorms this afternoon. Patchy fog this afternoon. Waves 4 to 6 ft occasionally to 8 ft. .TONIGHT...South winds 15 to 25 kt increasing to 30 kt. Patchy fog in the evening, then patchy dense fog overnight. Slight chance of showers and thunderstorms in the evening, then chance of showers and thunderstorms overnight. Waves 4 to 7 ft occasionally to 9 ft building to 5 to 8 ft occasionally to 10 ft. .TUESDAY...South winds to 30 kt becoming west 15 to 25 kt. Waves 6 to 9 ft occasionally to 12 ft. .TUESDAY NIGHT...Northwest winds 10 to 20 kt becoming north. Waves 4 to 7 ft occasionally to 9 ft subsiding to 3 to 5 ft. .WEDNESDAY...North winds 10 to 20 kt increasing to 15 to 25 kt. Waves 3 to 5 ft. .WEDNESDAY NIGHT...Northeast winds 10 to 20 kt. Waves 3 to 5 ft subsiding to 2 to 4 ft. .THURSDAY...East winds 10 to 20 kt becoming northeast. Waves 2 to 4 ft. .FRIDAY...East winds 10 to 20 kt diminishing to 10 to 15 kt. Waves 2 to 4 ft. $$ LMZ761-182115- MAFOR 1816/ MICHIGAN NORTH 11440 11430 12430 19434 11433 13440. A chance of showers late this morning. A chance of showers and thunderstorms overnight. A chance of showers Tuesday morning. Waves 3 to 5 feet this afternoon. Waves 3 to 6 feet building to 5 to 8 feet tonight. Waves 6 to 9 feet Tuesday morning. MICHIGAN SOUTH 15430 12440. A chance of showers this afternoon. A chance of showers and thunderstorms overnight. Waves 3 to 5 feet this afternoon. Waves 3 to 6 feet building to 4 to 7 feet tonight. Waves 6 to 9 feet Tuesday morning. $$ Kuroski Experimental modernized open lake forecast is available online at weather.gov/mkx/glftable Graphical marine forecasts are available online at: weather.gov/greatlakes