First, you may want to know a few facts about Tahoe. Lake Tahoe is the largest high alpine lake in the Northern Hemisphere. Tahoe is the tenth deepest lake in the world. Underwater visibility is approximately 70 feet. Summers are dry with occasional thunderstorms in August.
Winters are wet.
The mountains receive substantially more. An average year will have 275 to 300 days of sunshine a year. Although the shallow beach areas can warm up to 60 degrees in August, most of the lake stays 40 - 50 degrees year round. Swimmers can easily suffer from hypothermia so wetsuits are advised. The only outlet is the Truckee River in Tahoe City.