The highest day temperature in January 2026 was 67°F. The lowest night temperature was 39°F. The average values for day and night temperatures during January were 59.5°F и 45.4°F respectivly.

Most of the days in January are sunny but you can also expect cloudy and gloomy days.

Precipitation total in January for Napa is 1.2 in. It makes january one of the most rainy months of the year.

The average wind speed in January is 4.0 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Napa in January is 6.2 hours.