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. $$