Calistoga is approximately 70 miles north of San Francisco. You have a choice of two major airports to fly into:

SFO — San Francisco International Airport (84 miles south of Calistoga; 13 miles south of San Francisco)

OAK — Oakland International Airport (77 miles south of Calistoga; 21 miles southeast of San Francisco).

You may choose to fly into SJC, San Jose International Airport (116 miles south of Calistoga; 46 miles south of San Francisco), but it will add a considerable amount of time to your driving. I would only recommend this airport if your options are very limited.