715 FZUS61 KBUF 200802 GLFLO Open Lake Forecast for Lake Ontario National Weather Service Buffalo NY 402 AM EDT Wed May 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...Behind a passing cold front this morning, a large 30.4 inch area of surface high pressure will build across the entire Great Lakes region 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 late Friday night and Saturday, before weakening and sliding eastward Sunday. A 30.1 inch high will settle across the region Monday. LOZ062-201500- Lake Ontario open waters from the Niagara River to Hamlin Beach- 402 AM EDT Wed May 20 2026 .TODAY...Northwest winds 15 to 20 knots becoming west 10 to 15 knots. Waves 2 to 4 feet subsiding to 1 to 3 feet. .TONIGHT...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 less than 10 knots. Waves 1 foot or less. .FRIDAY...East winds 15 to 20 knots. Showers likely Friday night. Waves 1 to 3 feet building to 2 to 4 feet. .SATURDAY...East winds to 30 knots becoming southeast and diminishing to 15 to 20 knots. Showers. Waves 5 to 8 feet subsiding to 3 to 6 feet. Waves occasionally around 10 feet. .SUNDAY...Southeast winds 15 to 20 knots diminishing to 5 to 15 knots. Showers likely. Waves 2 to 4 feet subsiding to 1 to 3 feet. $$ LOZ063>065-201500- Lake Ontario open waters from Hamlin Beach to the Saint Lawrence River- 402 AM EDT Wed May 20 2026 .TODAY...West winds 15 to 20 knots. Waves 3 to 6 feet. .TONIGHT...West winds 15 to 20 knots becoming north. Waves 3 to 6 feet subsiding to 1 to 3 feet. .THURSDAY...Northeast winds 15 to 20 knots becoming northwest 5 to 15 knots. Waves 1 to 3 feet. .THURSDAY NIGHT...West winds less than 10 knots. Waves 1 foot or less. .FRIDAY...East winds 5 to 15 knots increasing to 15 to 20 knots. A chance of showers Friday night. Waves 1 to 3 feet. .SATURDAY...Southeast winds 15 to 25 knots. Showers. Waves 3 to 5 feet building to 4 to 7 feet, then subsiding to 3 to 6 feet. Waves occasionally around 9 feet. .SUNDAY...Southeast winds 15 to 25 knots. Showers likely. Waves 3 to 5 feet subsiding to 1 to 3 feet. $$ LOZ061-201500- MAFOR 2009/ ONTARIO WEST 1/2 11720 13620 13710 11800. Waves 2 to 4 feet today. Waves 2 to 4 feet subsiding to 1 to 2 feet tonight. ONTARIO EAST 1/2 14620 11620 11720 12810. Waves 2 to 4 feet building to 3 to 6 feet today. Waves 3 to 6 feet subsiding to 1 to 3 feet tonight. $$  737 FZUS61 KBUF 200803 GLFSL Forecast for the Saint Lawrence River including the Thousand Islands Region National Weather Service Buffalo NY 403 AM EDT Wed May 20 2026 SLZ022-024-201500- Saint Lawrence River from Cape Vincent to Saint Regis 403 AM EDT Wed May 20 2026 .TODAY...West winds 5 to 15 knots. Mostly cloudy early, then becoming mostly sunny. .TONIGHT...Northwest winds 5 to 10 knots becoming north. Mainly clear early, then becoming partly cloudy. .THURSDAY...North winds 10 knots or less. Sunny. .THURSDAY NIGHT...North winds less than 10 knots. Mainly clear in the evening, then becoming partly cloudy. .FRIDAY...East winds less than 10 knots. Partly cloudy, then becoming mostly cloudy. .SATURDAY...East winds 5 to 10 knots becoming southeast. A chance of showers during the day, then showers likely Saturday night. .SUNDAY...Southeast winds 5 to 10 knots becoming south. Showers likely. $$