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Monthly climate in Saint Helena, California, United States

Last updated: March 2, 2024

Under the Köppen–Geiger climate classification Saint Helena features a warm-summer Mediterranean climate (Csb). Temperatures typically range between 9 °C (49 °F) and 23 °C (74 °F) through the year, but rarely can drop to -3 °C (27 °F) or can rise to as high as 43 °C (109 °F). The average annual precipitation amounts to about 620 mm (24.4 inches) and receives 48 rainy days on the 1 mm (0.04 inches) threshold annually. Saint Helena enjoys an average of 3393 hours of sunshine throughout the year, and daylight varies from 9 hours 31 minutes to 14 hours 47 minutes per day.

Monthly average temperatures in Saint Helena, California, United States §

The warmest months in Saint Helena are June, July and August, with daily mean temperatures ranging from 22 to 23 °C (72 - 74 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 9 to 10 °C (49 - 51 °F) throughout the day. On average each year, Saint Helena experiences 136 days above 25 °C (77.0 °F) and 4 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Saint Helena, California, United States. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to June 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Maximum 25°C
(77°F)		 27°C
(80°F)		 29°C
(85°F)		 33°C
(92°F)		 37°C
(99°F)		 42°C
(107°F)		 40°C
(105°F)		 41°C
(106°F)		 43°C
(109°F)		 37°C
(99°F)		 29°C
(84°F)		 23°C
(74°F)
Mean maximum 21°C
(69°F)		 23°C
(74°F)		 26°C
(79°F)		 30°C
(86°F)		 33°C
(93°F)		 37°C
(100°F)		 38°C
(101°F)		 38°C
(101°F)		 39°C
(102°F)		 33°C
(91°F)		 25°C
(78°F)		 20°C
(68°F)
Average high 14°C
(58°F)		 17°C
(62°F)		 17°C
(64°F)		 21°C
(71°F)		 25°C
(77°F)		 30°C
(86°F)		 32°C
(89°F)		 31°C
(88°F)		 30°C
(86°F)		 26°C
(79°F)		 19°C
(66°F)		 14°C
(58°F)
Daily mean 9°C
(49°F)		 10°C
(51°F)		 11°C
(53°F)		 15°C
(59°F)		 18°C
(64°F)		 22°C
(72°F)		 23°C
(74°F)		 23°C
(73°F)		 21°C
(71°F)		 18°C
(64°F)		 12°C
(55°F)		 9°C
(49°F)
Average low 5°C
(42°F)		 5°C
(42°F)		 6°C
(43°F)		 9°C
(48°F)		 11°C
(53°F)		 15°C
(59°F)		 15°C
(60°F)		 16°C
(61°F)		 14°C
(58°F)		 11°C
(52°F)		 7°C
(45°F)		 5°C
(41°F)
Mean minimum -0°C
(32°F)		 -1°C
(31°F)		 1°C
(34°F)		 3°C
(38°F)		 7°C
(45°F)		 11°C
(51°F)		 13°C
(55°F)		 13°C
(55°F)		 10°C
(50°F)		 5°C
(42°F)		 1°C
(35°F)		 0°C
(33°F)
Minimum -1°C
(30°F)		 -3°C
(27°F)		 -1°C
(31°F)		 2°C
(36°F)		 4°C
(39°F)		 9°C
(49°F)		 12°C
(53°F)		 11°C
(52°F)		 7°C
(46°F)		 4°C
(40°F)		 -0°C
(31°F)		 -1°C
(30°F)

Compare climate in Saint Helena with other places

Compare temperature, precipitation, sunshine, UV index in Saint Helena, California, United States with other places around the world.

Monthly average precipitation in Saint Helena, California, United States §

Saint Helena usually has the most precipitation in January, February and December, with an average of 7 rainy days and 124 mm (4.9 inches) of precipitation per month. The driest months in Saint Helena are July, August and September. On average, 1 mm (0.0 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Saint Helena, California, United States. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average precipitation mm (inches) 137 (5.4) 141 (5.6) 92 (3.6) 39 (1.5) 23 (0.9) 2 (0.1) 0 (0.0) 0 (0.0) 2 (0.1) 38 (1.5) 51 (2.0) 95 (3.7)
Average precipitation days (≥ 1 mm) 8 7 10 5 3 0 0 0 0 2 5 8

Monthly sunshine hours in Saint Helena, California, United States §

The sunniest months in Saint Helena are May, June and July, when the sun shines an average of 12 hours 20 minutes a day. Least sunny months in Saint Helena: January, February and December receive an average of 5 hours 53 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Saint Helena, California, United States. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Mean monthly sunshine hours 141 209 256 295 356 384 394 355 314 279 219 185
Mean daily daylight hours 9h 49m 10h 46m 11h 59m 13h 13m 14h 16m 14h 47m 14h 30m 13h 34m 12h 22m 11h 8m 10h 3m 9h 31m

Solar UV radiation in Saint Helena, California, United States §

Saint Helena experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 10 - 11, which corresponds to the Very High / Extreme category of sun exposure. January, November and December are in the Moderate exposure category. In these months, the maximum values of the UV index do not exceed 4. For more detailed information, check out our hourly Saint Helena UV Index data.

Average daily maximum UV levels by month for Saint Helena, California, United States. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2022 to January 2023.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
UV Index (month maximum) 3 5 7 9 10 11 11 10 9 6 4 3

Detailed Monthly Weather Insights for Saint Helena, California, United States

Discover in-depth weather details for every month in Saint Helena. Click through the links below for comprehensive overviews of temperature trends, precipitation levels, sunshine hours, and solar UV radiation specifics. Whether planning a visit or simply curious about Saint Helena's climate nuances, these monthly breakdowns provide the information you need for an informed understanding of what to expect throughout the year.

Each link leads to a detailed account of the typical weather conditions for that month, providing both locals and tourists with vital information to plan their daily activities, wardrobe, and travel itineraries accordingly.