FZUS61 KBUF 192002 GLFLO Open Lake Forecast for Lake Ontario National Weather Service Buffalo NY 402 PM EDT Tue May 19 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 29.6 inch area of low pressure over western Quebec this evening will swing a cold front across the Lake late tonight. A large 30.4 inch area of surface high pressure will then build across the entire Great Lakes region Wednesday afternoon through Thursday, before sliding east off the New England coast late Friday. This surface high will then strengthen to 30.6 inches as it anchors over Atlantic Canada through Sunday. A 29.9 inch low and attendant warm front will then slowly approach the Lake later Friday night and Saturday, before weakening and sliding eastward Sunday with the large area of high pressure over Atlantic Canada. LOZ062-200300- Lake Ontario open waters from the Niagara River to Hamlin Beach- 402 PM EDT Tue May 19 2026 .TONIGHT...Southwest winds 15 to 20 knots becoming west. Showers with a chance of thunderstorms this evening, then a chance of showers after midnight. Showers likely late. Waves 3 to 5 feet. .WEDNESDAY...Northwest winds 10 to 15 knots becoming west. 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 5 to 15 knots becoming southeast. Waves 2 feet or less. .THURSDAY NIGHT...East winds 10 knots or less. Waves 1 foot 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. Showers likely. Waves 3 to 6 feet. .SUNDAY...East winds 5 to 15 knots becoming southwest less than 10 knots. Showers likely during the day, then a chance of showers Sunday night. Waves 1 to 3 feet subsiding to 1 foot or less. Winds and waves higher in and near thunderstorms. $$ LOZ063>065-200300- Lake Ontario open waters from Hamlin Beach to the Saint Lawrence River- 402 PM EDT Tue May 19 2026 .TONIGHT...Southwest winds 10 to 15 knots becoming west 15 to 20 knots. A chance of showers and thunderstorms early, then showers likely with a chance of thunderstorms late this evening. Showers likely after midnight. Waves 2 to 4 feet. .WEDNESDAY...West winds 15 to 20 knots. A chance of showers early. Waves 2 to 4 feet building to 3 to 6 feet. .WEDNESDAY NIGHT...West winds 15 to 20 knots becoming north 10 to 15 knots. Waves 3 to 6 feet subsiding to 1 to 3 feet. .THURSDAY...Northeast winds 5 to 15 knots becoming west. Waves 1 to 3 feet subsiding to 1 foot or less. .THURSDAY NIGHT...West winds less than 10 knots. Waves 1 foot or less. .FRIDAY...East winds 5 to 15 knots increasing to 15 to 20 knots. A chance of showers Friday night. Waves 1 to 3 feet. .SATURDAY...East winds 15 to 20 knots becoming southeast. Showers likely. Waves 3 to 5 feet subsiding to 2 to 4 feet. .SUNDAY...Southeast winds 15 to 20 knots becoming south 10 to 15 knots. Showers likely during the day, then a chance of showers Sunday night. Waves 2 to 4 feet subsiding to 1 to 3 feet. Winds and waves higher in and near thunderstorms. $$ LOZ061-200300- MAFOR 1921/ ONTARIO WEST 1/2 11520 11526 11520 11620 12610 12620. A chance of thunderstorms this evening. Waves 3 to 5 feet tonight. Waves 2 to 4 feet Wednesday. ONTARIO EAST 1/2 12510 12520 11610 13620. A chance of showers and thunderstorms this evening. A chance of showers overnight. Waves 1 to 3 feet building to 2 to 4 feet tonight. Waves 2 to 4 feet building to 3 to 6 feet Wednesday. $$