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Monthly climate in Guerneville, California, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Guerneville features a warm-summer Mediterranean climate (Csb).Temperatures typically range between 9 °C (49 °F) and 20 °C (68 °F) through the year, but rarely can drop to -3 °C (27 °F) or can rise to as high as 40 °C (103 °F).The average annual precipitation amounts to about 680 mm (26.8 inches) and receives 52 rainy days on the 1 mm (0.04 inches) threshold annually.Guerneville enjoys an average of 3326 hours of sunshine throughout the year, and daylight varies from 9 hours 30 minutes to 14 hours 47 minutes per day.

Monthly average temperatures in Guerneville, California, United States §

The warmest months in Guerneville are July, August and September, with daily mean temperatures ranging from 19 to 20 °C (67 - 68 °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, Guerneville experiences 78 days above 25 °C (77.0 °F) and 2 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Guerneville, 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)		 25°C
(77°F)		 26°C
(80°F)		 30°C
(86°F)		 33°C
(91°F)		 37°C
(99°F)		 35°C
(95°F)		 35°C
(96°F)		 40°C
(103°F)		 35°C
(94°F)		 27°C
(81°F)		 24°C
(75°F)
Mean maximum 20°C
(69°F)		 22°C
(72°F)		 24°C
(76°F)		 27°C
(81°F)		 30°C
(86°F)		 33°C
(92°F)		 33°C
(92°F)		 33°C
(92°F)		 35°C
(95°F)		 31°C
(88°F)		 24°C
(75°F)		 20°C
(68°F)
Average high 14°C
(58°F)		 16°C
(61°F)		 16°C
(62°F)		 19°C
(66°F)		 21°C
(71°F)		 25°C
(78°F)		 27°C
(80°F)		 26°C
(80°F)		 26°C
(79°F)		 24°C
(75°F)		 18°C
(65°F)		 14°C
(58°F)
Daily mean 10°C
(50°F)		 10°C
(51°F)		 11°C
(52°F)		 13°C
(57°F)		 16°C
(60°F)		 19°C
(67°F)		 20°C
(68°F)		 20°C
(68°F)		 19°C
(67°F)		 16°C
(62°F)		 12°C
(54°F)		 9°C
(49°F)
Average low 6°C
(43°F)		 5°C
(42°F)		 6°C
(44°F)		 9°C
(48°F)		 11°C
(51°F)		 14°C
(57°F)		 14°C
(58°F)		 15°C
(59°F)		 14°C
(57°F)		 10°C
(51°F)		 7°C
(44°F)		 5°C
(42°F)
Mean minimum 1°C
(33°F)		 -0°C
(32°F)		 1°C
(35°F)		 4°C
(40°F)		 7°C
(45°F)		 10°C
(50°F)		 12°C
(53°F)		 11°C
(52°F)		 9°C
(49°F)		 5°C
(42°F)		 0°C
(33°F)		 0°C
(33°F)
Minimum -1°C
(30°F)		 -3°C
(27°F)		 0°C
(32°F)		 3°C
(37°F)		 5°C
(41°F)		 9°C
(48°F)		 11°C
(53°F)		 10°C
(50°F)		 8°C
(47°F)		 3°C
(38°F)		 -1°C
(30°F)		 0°C
(32°F)

Compare climate in Guerneville with other places

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

Monthly average precipitation in Guerneville, California, United States §

Guerneville usually has the most precipitation in January, February and December, with an average of 8 rainy days and 133 mm (5.2 inches) of precipitation per month.The driest months in Guerneville are June, July and August. On average, 1 mm (0.0 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Guerneville, 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) 140 (5.5) 157 (6.2) 96 (3.8) 47 (1.9) 30 (1.2) 2 (0.1) 0 (0.0) 0 (0.0) 2 (0.1) 43 (1.7) 61 (2.4) 102 (4.0)
Average precipitation days (≥ 1 mm) 9 8 10 6 3 0 0 0 0 2 5 9

Monthly sunshine hours in Guerneville, California, United States §

The sunniest months in Guerneville are May, June and July, when the sun shines an average of 11 hours 57 minutes a day.Least sunny months in Guerneville: 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 Guerneville, 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 140 211 265 295 350 374 375 332 305 274 216 184
Mean daily daylight hours 9h 48m 10h 46m 11h 59m 13h 13m 14h 16m 14h 47m 14h 30m 13h 34m 12h 22m 11h 8m 10h 3m 9h 30m

Solar UV radiation in Guerneville, California, United States §

Guerneville 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 Guerneville UV Index data.

Average daily maximum UV levels by month for Guerneville, 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 8 10 11 11 10 9 6 4 3