Sonoma County has four distinct wine seasons. Each one has trade-offs.
Spring (March–May) is the best-value season. Mustard blooms in March, weather warms by May, and weekday tasting appointments are easy to book.
Summer (June–August) is peak tourist season. Reservations are required at most premium tasting rooms, and Saturday traffic on Highway 101 and Westside Road can be slow.
Harvest (September–October) is the most photogenic season. Crush is in full swing, lighting is golden, and the energy at wineries is electric — but Saturdays book out months in advance.
Winter (November–February) is the locals' favorite. Rates drop 20–40%, tasting rooms are quiet, and you can land a same-week reservation at Jordan or Iron Horse.
Whenever you come, hire a driver. Sonoma County is serious about DUI enforcement and the wineries are too good to taste with restraint.