FZUS61 KBUF 180804 GLFLO Open Lake Forecast for Lake Ontario National Weather Service Buffalo NY 403 AM EDT Sat Apr 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...A 30.0 inch high will push northeast across the Canadian Maritimes today. Meanwhile, a 29.4 inch low north of Lake Superior this morning will move to James Bay and deepen to 29.0 inches during the day, while pushing a trailing strong cold front across the Lake this afternoon and evening. A 30.4 inch high will then settle southeastward across the Great Lakes Sunday through Monday night, before sliding off the mid-Atlantic coast Tuesday. A 29.4 inch low over lower Hudson Bay Tuesday, will weaken to 29.9 inches by Wednesday, while pushing an attendant weak cold front across the Lake Tuesday night. A 30.2 inch high will then build across the Great Lakes region Wednesday and Thursday. LOZ062-181500- Lake Ontario open waters from the Niagara River to Hamlin Beach- 403 AM EDT Sat Apr 18 2026 .TODAY...Southeast winds 10 to 15 knots becoming southwest 15 to 20 knots. Showers likely early this afternoon. Showers with a chance of thunderstorms late. Some thunderstorms may produce gusty winds late. Waves 1 to 3 feet building to 2 to 4 feet. .TONIGHT...West winds 15 to 20 knots becoming northwest 10 to 15 knots. Rain showers likely. Waves 2 to 4 feet. .SUNDAY...West winds 10 to 15 knots increasing to 15 to 20 knots. A chance of rain and snow showers in the afternoon. Waves 1 to 3 feet building to 2 to 4 feet. .SUNDAY NIGHT...West winds 15 to 20 knots becoming northwest. A chance of rain showers in the evening. Waves 3 to 5 feet. .MONDAY...Northwest winds 15 to 20 knots becoming southwest 5 to 15 knots. Waves 2 to 4 feet subsiding to 1 to 3 feet. .TUESDAY...South winds 15 to 20 knots becoming northwest 10 to 15 knots. A chance of rain showers. Waves 1 to 3 feet building to 2 to 4 feet, then subsiding to 1 to 3 feet. .WEDNESDAY...North winds 10 knots or less. Waves 2 feet or less. Winds and waves higher in and near thunderstorms. $$ LOZ063>065-181500- Lake Ontario open waters from Hamlin Beach to the Saint Lawrence River- 403 AM EDT Sat Apr 18 2026 .TODAY...Southeast winds 15 to 20 knots becoming south. Showers likely late. Waves 1 to 3 feet building to 3 to 5 feet. .TONIGHT...Southwest winds 15 to 20 knots becoming northwest 10 to 15 knots. Rain showers with a chance of thunderstorms early, then rain showers from late evening on. Some thunderstorms may produce gusty winds early. Waves 3 to 5 feet subsiding to 2 to 4 feet. .SUNDAY...West winds 10 to 15 knots increasing to 15 to 20 knots. Rain and snow showers likely in the morning, then a chance of snow showers in the afternoon. Waves 1 to 3 feet building to 3 to 6 feet. .SUNDAY NIGHT...West winds 15 to 20 knots becoming northwest. Waves 3 to 6 feet. .MONDAY...Northwest winds 15 to 20 knots becoming west and diminishing to 5 to 10 knots. Waves 3 to 6 feet subsiding to 1 to 3 feet. .TUESDAY...South winds 10 to 15 knots becoming west. A chance of rain showers. Waves 1 to 3 feet. .WEDNESDAY...North winds 5 to 15 knots. Waves 1 to 3 feet subsiding to 1 foot or less. Winds and waves higher in and near thunderstorms. $$ LOZ061-181500- MAFOR 1809/ ONTARIO WEST 1/2 11310 11410 11420 11426 11626 11620 12710. A chance of thunderstorms this afternoon. Waves 1 to 3 feet building to 2 to 4 feet today. Waves 2 to 4 feet tonight. ONTARIO EAST 1/2 11310 11320 12420 11426 11626 11610 11716. Waves 1 to 3 feet building to 3 to 5 feet today. Waves 3 to 5 feet subsiding to 2 to 4 feet tonight. $$