SXUS45 KMSO 202330 RECGPI Recreation Forecast for Flathead Lake National Weather Service Missoula MT 505 PM MDT Fri Mar 20 2026 Note: The experimental wave height forecasts are representative of the mid lake waters and downwind shores. Wave heights may be significantly less on upwind shores. .Tonight...Breezy. Mostly cloudy. A chance of rain until early morning, then rain likely late in the night. Lows in the upper 40s. South winds 15 to 20 mph. Gusts up to 35 mph in the evening. Chance of rain 70 percent. Waves around 1 foot...locally up to 2 feet. .SATURDAY...Breezy. Cloudy with a chance of rain in the morning, then partly sunny with a slight chance of rain in the afternoon. Highs in the lower 50s. South winds around 15 mph shifting to the southwest 15 to 25 mph with gusts to around 30 mph in the afternoon. Chance of rain 50 percent. Waves around 1 foot... locally up to 2 feet. .SATURDAY NIGHT...Colder. Mostly clear. Lows in the upper 30s. Southwest winds around 15 mph with gusts to around 30 mph in the evening becoming light. Waves around 1 foot...locally up to 2 feet. .SUNDAY...Sunny. Highs around 50 . Southwest winds around 15 mph. Waves around 1 foot...locally up to 2 feet.