RECMKX Recreational Boater Forecast for Inland Lakes for Southeast Wisconsin National Weather Service Milwaukee/Sullivan WI 317 CDT Thu Sep 10 2026 ...Lake Koshkonong... .TODAY... Waves...............Nearly calm. Sky/Weather.........Mostly sunny. Max Temperature.....Around 78. Winds...............North winds up to 5 mph. Water Temperature...69 degrees. UV Index............5 - Moderate. .TONIGHT... Waves...............Half foot to 1 foot. Sky/Weather.........Mostly clear. Min Temperature.....Around 56. Winds...............South winds up to 5 mph. Water Temperature...69 degrees. UV Index............5 - Moderate. .FRIDAY... Waves...............Half foot to 1 foot. Sky/Weather.........Sunny. Max Temperature.....Upper 70s. Winds...............South winds around 10 mph. .SATURDAY... Waves...............Half foot to 1 foot. Sky/Weather.........Partly sunny. Slight chance of showers. Max Temperature.....Around 80. Winds...............West winds around 10 mph. .SUNDAY... Waves...............Half foot to 1 foot. Sky/Weather.........Partly sunny. Slight chance of showers. Max Temperature.....Mid 70s. Winds...............Northeast winds around 5 mph. Sunrise: 06:29 AM CDT Sunset: 07:17 PM CDT $$