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Monthly climate in Janesville, California, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Janesville features a warm-summer Mediterranean climate (Csb).Temperatures typically range between -1 °C (31 °F) and 23 °C (74 °F) through the year, but rarely can drop to -20 °C (-4 °F) or can rise to as high as 38 °C (100 °F).The average annual precipitation amounts to about 584 mm (23.0 inches) and receives 76 rainy days on the 1 mm (0.04 inches) threshold annually.Janesville enjoys an average of 3440 hours of sunshine throughout the year, and daylight varies from 9 hours 20 minutes to 14 hours 59 minutes per day.

Monthly average temperatures in Janesville, California, United States §

The warmest months in Janesville are June, July and August, with daily mean temperatures ranging from 19 to 23 °C (66 - 74 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from -1 to 0 °C (31 - 32 °F) throughout the day. On average each year, Janesville experiences 89 days above 25 °C (77.0 °F) and 130 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Janesville, 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 11°C
(52°F)		 17°C
(62°F)		 20°C
(68°F)		 27°C
(80°F)		 31°C
(89°F)		 36°C
(98°F)		 38°C
(100°F)		 36°C
(98°F)		 36°C
(97°F)		 29°C
(85°F)		 22°C
(72°F)		 13°C
(55°F)
Mean maximum 10°C
(50°F)		 12°C
(55°F)		 17°C
(63°F)		 23°C
(74°F)		 28°C
(83°F)		 31°C
(89°F)		 36°C
(97°F)		 35°C
(96°F)		 34°C
(93°F)		 25°C
(78°F)		 20°C
(68°F)		 10°C
(51°F)
Average high 4°C
(40°F)		 6°C
(43°F)		 9°C
(48°F)		 14°C
(58°F)		 19°C
(67°F)		 26°C
(79°F)		 32°C
(89°F)		 31°C
(88°F)		 25°C
(78°F)		 18°C
(64°F)		 11°C
(51°F)		 4°C
(40°F)
Daily mean -0°C
(32°F)		 0°C
(32°F)		 2°C
(37°F)		 8°C
(46°F)		 12°C
(55°F)		 19°C
(66°F)		 23°C
(74°F)		 22°C
(72°F)		 17°C
(63°F)		 10°C
(50°F)		 4°C
(40°F)		 -1°C
(31°F)
Average low -5°C
(24°F)		 -5°C
(23°F)		 -3°C
(26°F)		 1°C
(34°F)		 5°C
(42°F)		 10°C
(51°F)		 14°C
(58°F)		 14°C
(57°F)		 9°C
(49°F)		 3°C
(38°F)		 -0°C
(31°F)		 -5°C
(23°F)
Mean minimum -14°C
(8°F)		 -13°C
(8°F)		 -11°C
(12°F)		 -5°C
(23°F)		 -0°C
(32°F)		 3°C
(37°F)		 11°C
(51°F)		 9°C
(49°F)		 3°C
(37°F)		 -3°C
(27°F)		 -7°C
(20°F)		 -12°C
(11°F)
Minimum -20°C
(-4°F)		 -17°C
(2°F)		 -17°C
(1°F)		 -11°C
(12°F)		 -3°C
(27°F)		 -0°C
(32°F)		 9°C
(49°F)		 7°C
(46°F)		 -1°C
(30°F)		 -6°C
(22°F)		 -11°C
(13°F)		 -14°C
(7°F)

Compare climate in Janesville with other places

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

Monthly average precipitation in Janesville, California, United States §

Janesville usually has the most precipitation in January, February and March, with an average of 10 rainy days and 99 mm (3.9 inches) of precipitation per month.The driest months in Janesville are June, July and August. On average, 8 mm (0.3 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Janesville, 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) 102 (4.0) 110 (4.3) 85 (3.4) 43 (1.7) 44 (1.7) 10 (0.4) 7 (0.3) 8 (0.3) 19 (0.7) 34 (1.3) 47 (1.8) 75 (3.0)
Average precipitation days (≥ 1 mm) 10 10 12 8 8 2 2 3 3 3 6 9

Monthly sunshine hours in Janesville, California, United States §

The sunniest months in Janesville are June, July and August, when the sun shines an average of 12 hours 30 minutes a day.Least sunny months in Janesville: January, February and December receive an average of 5 hours 59 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Janesville, 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 144 210 261 305 355 389 398 362 320 282 219 190
Mean daily daylight hours 9h 39m 10h 40m 11h 58m 13h 18m 14h 25m 14h 59m 14h 40m 13h 40m 12h 23m 11h 4m 9h 55m 9h 20m

Solar UV radiation in Janesville, California, United States §

Janesville experiences the highest level of ultraviolet (UV) radiation in May, June and August, when the maximum UV index can reach values of 11 - 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 4. For more detailed information, check out our hourly Janesville UV Index data.

Average daily maximum UV levels by month for Janesville, 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 5 8 9 11 12 11 11 9 7 4 3