FZUS61 KBUF 202003 GLFSL Forecast for the Saint Lawrence River including the Thousand Islands Region National Weather Service Buffalo NY 403 PM EDT Sun Sep 20 2026 SLZ022-024-210300- Saint Lawrence River from Cape Vincent to Saint Regis 403 PM EDT Sun Sep 20 2026 .TONIGHT...Northeast winds less than 10 knots becoming north 10 to 15 knots. Partly to mostly cloudy. .MONDAY...North winds 5 to 15 knots becoming northeast. Partly sunny in the morning, then becoming mostly cloudy. .MONDAY NIGHT...Northeast winds 5 to 10 knots. Mostly cloudy. .TUESDAY...Northeast winds 5 to 10 knots. Sunny. .TUESDAY NIGHT...Northeast winds 5 to 10 knots. Mainly clear. .WEDNESDAY...Northeast winds 10 knots or less. Mainly clear. .THURSDAY...Northeast winds 10 knots or less. Partly cloudy. .FRIDAY...Northeast winds 10 knots or less becoming north. Partly cloudy. $$