Lake Tahoe works year-round but each season has its trade-offs.
Winter (December–March) is ski season. Snowpack can be exceptional in a good year — Palisades and Heavenly regularly record more than 400 inches annually. The roads stay open except during major storms, when chains or 4WD are required on I-80 and Highway 50. Book accommodation well in advance for holiday weekends.
Summer (July–August) is busy but justifiably so. The lake water reaches a swimmable 65°F, wildflowers fill the high meadows, and all the restaurants and services are open. Traffic on weekends is serious — the two main access roads (I-80 via Truckee and Highway 50 via South Lake Tahoe) both congest badly.
Shoulder seasons (May–June, September–October) are the best for avoiding crowds. The lake water is clearest in late September, the aspen groves on the Nevada side go gold in October, and the ski resorts have already closed so the towns are quiet. May can still have significant snow above 7,000 feet, which closes some high trails.