All seasons are extremely enjoyable in Calistoga. Winter is an excellent time to feel the warmth of the geothermal water during cool, rainy days. Spring and Summer provide longer, warmer days and cool evenings, perfect for outdoor activities. And lastly, fall is one of the best times to visit Calistoga, California. September and October - when you'll be able to see the wineries in full production mode. The weather is beautiful at this time of year, with temperatures in the 70s and 80s.