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Monthly climate in Portola, California, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Portola features a warm-summer Mediterranean climate (Csb).Temperatures typically range between -2 °C (29 °F) and 21 °C (70 °F) through the year, but rarely can drop to -19 °C (-2 °F) or can rise to as high as 35 °C (95 °F).The average annual precipitation amounts to about 928 mm (36.5 inches) and receives 87 rainy days on the 1 mm (0.04 inches) threshold annually.Portola enjoys an average of 3465 hours of sunshine throughout the year, and daylight varies from 9 hours 23 minutes to 14 hours 55 minutes per day.

Monthly average temperatures in Portola, California, United States §

The warmest months in Portola are June, July and August, with daily mean temperatures ranging from 16 to 21 °C (62 - 70 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from -2 to -1 °C (29 - 31 °F) throughout the day. On average each year, Portola experiences 73 days above 25 °C (77.0 °F) and 157 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Portola, 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 13°C
(56°F)		 16°C
(61°F)		 18°C
(64°F)		 25°C
(76°F)		 28°C
(83°F)		 33°C
(92°F)		 35°C
(95°F)		 35°C
(94°F)		 34°C
(94°F)		 29°C
(84°F)		 23°C
(74°F)		 14°C
(58°F)
Mean maximum 10°C
(50°F)		 12°C
(53°F)		 15°C
(60°F)		 21°C
(71°F)		 26°C
(79°F)		 29°C
(85°F)		 33°C
(92°F)		 33°C
(92°F)		 32°C
(90°F)		 25°C
(77°F)		 20°C
(68°F)		 11°C
(52°F)
Average high 4°C
(40°F)		 5°C
(42°F)		 7°C
(45°F)		 12°C
(54°F)		 17°C
(63°F)		 24°C
(75°F)		 29°C
(85°F)		 28°C
(84°F)		 24°C
(75°F)		 17°C
(63°F)		 11°C
(51°F)		 4°C
(40°F)
Daily mean -1°C
(31°F)		 -1°C
(30°F)		 1°C
(34°F)		 5°C
(41°F)		 10°C
(51°F)		 16°C
(62°F)		 21°C
(70°F)		 20°C
(68°F)		 15°C
(60°F)		 8°C
(47°F)		 3°C
(38°F)		 -2°C
(29°F)
Average low -5°C
(23°F)		 -6°C
(21°F)		 -4°C
(25°F)		 -1°C
(30°F)		 3°C
(38°F)		 8°C
(47°F)		 12°C
(54°F)		 12°C
(53°F)		 7°C
(45°F)		 1°C
(34°F)		 -3°C
(27°F)		 -7°C
(20°F)
Mean minimum -15°C
(6°F)		 -15°C
(4°F)		 -13°C
(9°F)		 -9°C
(16°F)		 -3°C
(26°F)		 0°C
(33°F)		 7°C
(45°F)		 7°C
(45°F)		 0°C
(33°F)		 -5°C
(23°F)		 -10°C
(14°F)		 -15°C
(6°F)
Minimum -19°C
(-1°F)		 -19°C
(-2°F)		 -19°C
(-2°F)		 -12°C
(11°F)		 -7°C
(20°F)		 -4°C
(26°F)		 5°C
(41°F)		 6°C
(43°F)		 -2°C
(28°F)		 -8°C
(17°F)		 -13°C
(9°F)		 -17°C
(1°F)

Compare climate in Portola with other places

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

Monthly average precipitation in Portola, California, United States §

Portola usually has the most precipitation in January, February and March, with an average of 12 rainy days and 164 mm (6.5 inches) of precipitation per month.The driest months in Portola are June, July and August. On average, 11 mm (0.4 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Portola, 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) 170 (6.7) 177 (7.0) 146 (5.7) 72 (2.8) 60 (2.3) 10 (0.4) 10 (0.4) 13 (0.5) 19 (0.7) 43 (1.7) 79 (3.1) 132 (5.2)
Average precipitation days (≥ 1 mm) 11 11 15 8 9 3 3 4 3 3 7 10

Monthly sunshine hours in Portola, California, United States §

The sunniest months in Portola are June, July and August, when the sun shines an average of 12 hours 32 minutes a day.Least sunny months in Portola: January, February and December receive an average of 6 hours 6 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Portola, 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 150 212 259 307 356 390 398 364 321 286 225 192
Mean daily daylight hours 9h 42m 10h 42m 11h 58m 13h 17m 14h 23m 14h 55m 14h 37m 13h 38m 12h 23m 11h 5m 9h 57m 9h 23m

Solar UV radiation in Portola, California, United States §

Portola experiences the highest level of ultraviolet (UV) radiation in May, June and July, when the maximum UV index can reach values of 12 - 12, which corresponds to the 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 5. For more detailed information, check out our hourly Portola UV Index data.

Average daily maximum UV levels by month for Portola, 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) 4 6 9 10 12 12 12 11 10 7 5 3