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Climate · Napa

Napa in September

Hot and dry, as the days shorten.

Typical weather, averaged over 30 years

September in Napa is hot: highs near 90°F, lows near 58°F. Rain is rare, and the days shorten by 53 minutes from the first week to the last.September in Napa is hot: highs near 32°C, lows near 14°C. Rain is rare, and the days shorten by 53 minutes from the first week to the last.

High
90°F32°Caverage
Low
58°F14°Caverage
Wet days
0a week · 3% of days
Daylight
12h 21mon average

Is September a good time to visit Napa?

September sits outside Napa's best months, which run in two parts: April to May, or October to November. Expect hot days and rain on fewer than one day a week.

How we judge it: every month is scored on how close its typical high comes to the range from 70°F to 80°F, how mild its nights are, and how rarely it rains. The best months are the run of months that scores best.How we judge it: every month is scored on how close its typical high comes to the range from 21°C to 27°C, how mild its nights are, and how rarely it rains. The best months are the run of months that scores best.

How September sits in the year

week by week

Temperature

Highs near 90°F in September, against 62°F to 92°F through the year.Highs near 32°C in September, against 17°C to 33°C through the year.

Chance of a wet day

3% of days in September, against 0% to 34% through the year.

Cloud cover

15% cover in September, against 11% to 59% through the year.

Daylight

12h 21m in September, against 9h 32m to 14h 47m through the year.

Week by week, lightly smoothed, with September shaded. The olive line marks the best months. Hover or tap a week for its figures.

Either side

  1. August92°33°low 58°low 14°no wet daysRain on fewer than one day a week.
  2. September90°32°low 58°low 14°no wet daysRain on fewer than one day a week.
  3. October84°29°low 55°low 13°no wet daysRain on fewer than one day a week.

Where Napa sits, in September

America/Los Angeles
this place
typical high in September 40°F4°C95°F35°C
Sunrise, mid-September
6:50 AMsets 7:19 PM
Above the sea
0 mlow-lying
Latitude
38.3°Nnorthern hemisphere
Nearest of ours
Marshall55 km west

The land around Napa, shaded by its typical high in September, the planning map's own layer. Hover the map for the figure at that spot; tap it on a phone. Clock times are local, for the 15th.

Elsewhere in United States in September

high · low · wet days
See September on the planning mapThe whole year in Napa

Typical weather, averaged over 30 years (1995–2024), from the 11 km grid square nearest Napa. Temperatures are adjusted against 66 weather stations: daytime highs read about 3.1°F cold in the source data and are raised to match, and both highs and lows are adjusted for the town's height (0 m) against the climate model's (136 m).Temperatures are adjusted against 66 weather stations: daytime highs read about 1.7°C cold in the source data and are raised to match, and both highs and lows are adjusted for the town's height (0 m) against the climate model's (136 m). Daylight is calculated from latitude. Charts are lightly smoothed week to week; the figures in the table are not. Source: Copernicus ERA5-Land reanalysis; cloud cover from NASA's MERRA-2 reanalysis, on a coarser grid of about 50 km. Contains modified Copernicus Climate Change Service information 2026; neither the European Commission nor ECMWF is responsible for any use of it. These are averages, not a forecast.

Daylight is calculated from latitude. Charts are lightly smoothed week to week; the figures in the table are not.

Source: Copernicus ERA5-Land reanalysis; cloud cover from NASA's MERRA-2 reanalysis, on a coarser grid of about 50 km. Contains modified Copernicus Climate Change Service information 2026; neither the European Commission nor ECMWF is responsible for any use of it. These are averages, not a forecast.