FZUS61 KBUF 190202 GLFLO Open Lake Forecast for Lake Ontario National Weather Service Buffalo NY 1002 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 at 29.7 inches over Wisconsin will track 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. LOZ062-190900- Lake Ontario open waters from the Niagara River to Hamlin Beach- 1002 PM EDT Mon May 18 2026 .OVERNIGHT...Southwest winds 10 to 15 knots. A chance of showers. 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. $$ LOZ063>065-190900- Lake Ontario open waters from Hamlin Beach to the Saint Lawrence River- 1002 PM EDT Mon May 18 2026 .OVERNIGHT...South winds 5 to 15 knots becoming southwest. A chance of showers. Waves 2 feet or less. .TUESDAY...Southwest winds 10 to 15 knots. Waves 1 to 3 feet building to 2 to 4 feet. .TUESDAY NIGHT...Southwest winds 15 to 20 knots becoming west. Showers likely with a chance of thunderstorms in the evening, then showers likely overnight. Waves 2 to 4 feet building to 3 to 5 feet. .WEDNESDAY...West winds 15 to 25 knots. A chance of showers in the morning. Waves 3 to 6 feet building to 4 to 7 feet. Waves occasionally around 9 feet. .WEDNESDAY NIGHT...West winds 15 to 20 knots becoming north 10 to 15 knots. Waves 4 to 7 feet subsiding to 2 to 4 feet. Waves occasionally around 9 feet. .THURSDAY...North winds 5 to 15 knots becoming east less than 10 knots. Waves 1 to 3 feet subsiding to 1 foot or less. .FRIDAY...East winds 5 to 15 knots. A chance of showers Friday night. Waves 1 to 3 feet. .SATURDAY...Southeast winds 15 to 20 knots diminishing to 10 to 15 knots. Showers likely. Waves 2 to 4 feet building to 3 to 5 feet, then subsiding to 1 to 3 feet. Winds and waves higher in and near thunderstorms. $$ LOZ061-190900- MAFOR 1903/ ONTARIO WEST 1/2 14510 13520 11526. Waves 1 to 3 feet overnight. Waves 1 to 3 feet building to 3 to 5 feet Tuesday. Waves 3 to 5 feet Tuesday evening. ONTARIO EAST 1/2 13510 11500 13510 11520. A chance of showers late this evening. A chance of showers and thunderstorms Tuesday evening. Waves 2 feet or less overnight. Waves 1 to 3 feet Tuesday. Waves 2 to 4 feet Tuesday evening. $$