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St. Helena, CA weather and climate

Napa County, CA · population 5,378 · about 223 ft elevation

Everything below is a 30 year average for 1991-2020, computed from daily climate history at St. Helena's own coordinates.

The year at a glance

Sunny days
259
clear or partly cloudy, per year
Precipitation
27 in
per year
Wet days
58
rain or snow per year
Snowfall
0 in
per year
Hot days
54
above 90 °F
Freezing nights
14
at or below 32 °F
Humidity
66%
average relative
Average temperature
61 °F
year round

Monthly temperatures

Average daily high and low for each month, in °F.

Daily highDaily low
406080JanMarMayJulSepNovDaily high, Jan: 59 °FDaily high, Feb: 62 °FDaily high, Mar: 67 °FDaily high, Apr: 72 °FDaily high, May: 78 °FDaily high, Jun: 85 °FDaily high, Jul: 89 °FDaily high, Aug: 89 °FDaily high, Sep: 87 °FDaily high, Oct: 78 °FDaily high, Nov: 66 °FDaily high, Dec: 58 °FDaily low, Jan: 40 °FDaily low, Feb: 42 °FDaily low, Mar: 44 °FDaily low, Apr: 46 °FDaily low, May: 51 °FDaily low, Jun: 54 °FDaily low, Jul: 56 °FDaily low, Aug: 56 °FDaily low, Sep: 54 °FDaily low, Oct: 49 °FDaily low, Nov: 44 °FDaily low, Dec: 40 °F
View monthly temperatures as a table
Monthly temperatures (°F)
CityJanFebMarAprMayJunJulAugSepOctNovDec
Daily high596267727885898987786658
Daily low404244465154565654494440

Monthly precipitation

Total rain plus melted snow for each month, in inches.

0.02.04.0JanMarMayJulSepNovSt. Helena, Jan: 5.4 inSt. Helena, Feb: 5.4 inSt. Helena, Mar: 4.0 inSt. Helena, Apr: 1.7 inSt. Helena, May: 1.0 inSt. Helena, Jun: 0.3 inSt. Helena, Jul: 0.0 inSt. Helena, Aug: 0.0 inSt. Helena, Sep: 0.1 inSt. Helena, Oct: 1.3 inSt. Helena, Nov: 2.7 inSt. Helena, Dec: 5.5 in
View monthly precipitation as a table
Monthly precipitation (inches)
CityJanFebMarAprMayJunJulAugSepOctNovDec
St. Helena5.45.44.01.71.00.30.00.00.11.32.75.5

Monthly sunny days

Days each month with clear or partly cloudy skies.

0102030JanMarMayJulSepNovSt. Helena, Jan: 14 daysSt. Helena, Feb: 13 daysSt. Helena, Mar: 16 daysSt. Helena, Apr: 19 daysSt. Helena, May: 24 daysSt. Helena, Jun: 27 daysSt. Helena, Jul: 30 daysSt. Helena, Aug: 30 daysSt. Helena, Sep: 28 daysSt. Helena, Oct: 25 daysSt. Helena, Nov: 18 daysSt. Helena, Dec: 15 days
View monthly sunny days as a table
Monthly sunny days (days)
CityJanFebMarAprMayJunJulAugSepOctNovDec
St. Helena141316192427303028251815

Compare St. Helena with another city

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About this data

Figures are 30 year averages for 1991-2020. Wet days count days with measurable precipitation, calibrated against the wet day counts in NOAA's published climate normals. Sunny days count clear plus partly cloudy days, defined as average cloud cover of 63 percent or less and calibrated against NOAA's published sky cover tables. Snowfall figures are model estimates anchored to NOAA station measurements near each city.

Weather data by Open-Meteo.com (CC BY 4.0). Contains modified Copernicus Climate Change Service information (ERA5, ERA5-Land).