In January, things tend to slow down in the Wine Country and it is an excellent time to visit the Napa Valley. The traffic is usually light, the crowds have largely disappeared, and while you can expect some rain, the weather is often dry and sunny for extended periods.
The average temperature in Calistoga in January is 49 degrees with an average high of 60, and an average low of 37 degrees. The average rainfall in Calistoga for January is 8 inches.
Weather conditions suggest that you should pack a raincoat and a sweater. If you are coming from the East or Midwest, you will be envious of our mild winter conditions, and will be amused when you hear locals complain about how cold it is—on a January day when the temperature hits 55 degrees and the daffodils are beginning to bloom.