FZUS61 KBUF 210203 GLFLO Open Lake Forecast for Lake Ontario National Weather Service Buffalo NY 1003 PM EDT Mon Apr 20 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 30.4 inch high will settle southeast across the Great Lakes tonight, 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 a cold front across the lake Tuesday night. A 30.2 inch high will then build across the Great Lakes region Wednesday and Thursday. A warm front will approach the lake by Friday. A 29.6 inch low may move southwest of the lake on Saturday. LOZ062-210900- Lake Ontario open waters from the Niagara River to Hamlin Beach- 1003 PM EDT Mon Apr 20 2026 .OVERNIGHT...Southwest winds 10 knots or less becoming south. Waves 2 feet or less. .TUESDAY...South winds 10 to 15 knots. Waves 1 to 2 feet. .TUESDAY NIGHT...Southeast winds 5 to 10 knots becoming northeast. Waves 2 feet or less. .WEDNESDAY...Northeast winds 10 knots or less becoming southwest. Waves 1 foot or less. .WEDNESDAY NIGHT...West winds less than 10 knots becoming north. Waves 1 foot or less. .THURSDAY...Northeast winds 10 knots or less becoming east. Waves 1 foot or less. .FRIDAY...East winds 10 to 15 knots increasing to 15 to 20 knots. A chance of showers Friday night. Waves 1 to 3 feet building to 2 to 4 feet. .SATURDAY...East winds 15 to 20 knots becoming northeast 10 to 15 knots. A chance of showers. Waves 2 to 4 feet. $$ LOZ063>065-210900- Lake Ontario open waters from Hamlin Beach to the Saint Lawrence River- 1003 PM EDT Mon Apr 20 2026 .OVERNIGHT...West winds 5 to 15 knots becoming southwest. Waves 2 to 4 feet subsiding to 1 to 3 feet. .TUESDAY...South winds 10 to 15 knots becoming southeast. Waves 1 to 2 feet. .TUESDAY NIGHT...Southeast winds 10 to 15 knots. Waves 1 to 3 feet. .WEDNESDAY...East winds 10 knots or less becoming northwest. Waves 1 foot or less. .WEDNESDAY NIGHT...West winds less than 10 knots becoming north. Waves 1 foot or less. .THURSDAY...North winds 10 knots or less becoming northeast. Waves 1 foot or less. .FRIDAY...Northeast winds 5 to 15 knots becoming east. A chance of showers Friday night. Waves 1 to 3 feet. .SATURDAY...East winds 15 to 20 knots diminishing to 10 to 15 knots. A chance of showers. Waves 2 to 4 feet subsiding to 1 to 3 feet. $$ LOZ061-210900- MAFOR 2103/ ONTARIO WEST 1/2 11500 11400 13410 11310 12300. Waves 2 feet or less. ONTARIO EAST 1/2 11610 12500 12410 11300 11310 11410. Waves 2 to 4 feet subsiding to 1 to 3 feet overnight. Waves 1 to 2 feet Tuesday and Tuesday evening. $$