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Monthly climate in Janesville, Wisconsin, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Janesville features a humid continental climate (Dfa).Temperatures typically range between -6 °C (22 °F) and 24 °C (75 °F) through the year, but rarely can drop to -33 °C (-26 °F) or can rise to as high as 34 °C (94 °F).The average annual precipitation amounts to about 1002 mm (39.5 inches) and receives 122 rainy days on the 1 mm (0.04 inches) threshold annually.Janesville enjoys an average of 2929 hours of sunshine throughout the year, and daylight varies from 9 hours 4 minutes to 15 hours 15 minutes per day.

Monthly average temperatures in Janesville, Wisconsin, United States §

The warmest months in Janesville are June, July and August, with daily mean temperatures ranging from 22 to 24 °C (71 - 75 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from -6 to -1 °C (22 - 30 °F) throughout the day. On average each year, Janesville experiences 80 days above 25 °C (77.0 °F) and 123 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, Wisconsin, 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 12°C
(54°F)		 20°C
(68°F)		 23°C
(73°F)		 27°C
(81°F)		 34°C
(93°F)		 34°C
(93°F)		 34°C
(94°F)		 34°C
(93°F)		 33°C
(92°F)		 30°C
(86°F)		 23°C
(74°F)		 19°C
(66°F)
Mean maximum 9°C
(48°F)		 12°C
(54°F)		 18°C
(65°F)		 25°C
(77°F)		 31°C
(87°F)		 32°C
(90°F)		 33°C
(92°F)		 32°C
(89°F)		 31°C
(88°F)		 28°C
(83°F)		 17°C
(63°F)		 14°C
(58°F)
Average high -2°C
(29°F)		 -0°C
(32°F)		 7°C
(46°F)		 13°C
(56°F)		 20°C
(69°F)		 26°C
(80°F)		 28°C
(83°F)		 27°C
(81°F)		 24°C
(75°F)		 16°C
(61°F)		 7°C
(44°F)		 3°C
(37°F)
Daily mean -6°C
(22°F)		 -5°C
(24°F)		 3°C
(37°F)		 8°C
(47°F)		 15°C
(60°F)		 22°C
(71°F)		 24°C
(75°F)		 22°C
(72°F)		 19°C
(66°F)		 11°C
(52°F)		 3°C
(37°F)		 -1°C
(30°F)
Average low -9°C
(15°F)		 -10°C
(15°F)		 -2°C
(29°F)		 3°C
(38°F)		 11°C
(51°F)		 17°C
(62°F)		 19°C
(67°F)		 17°C
(63°F)		 14°C
(57°F)		 7°C
(45°F)		 -1°C
(30°F)		 -5°C
(24°F)
Mean minimum -24°C
(-11°F)		 -24°C
(-11°F)		 -15°C
(6°F)		 -4°C
(24°F)		 2°C
(36°F)		 12°C
(53°F)		 14°C
(57°F)		 12°C
(53°F)		 6°C
(43°F)		 -2°C
(28°F)		 -10°C
(14°F)		 -15°C
(6°F)
Minimum -32°C
(-25°F)		 -33°C
(-26°F)		 -23°C
(-9°F)		 -8°C
(17°F)		 -1°C
(30°F)		 8°C
(47°F)		 12°C
(54°F)		 9°C
(48°F)		 3°C
(37°F)		 -5°C
(24°F)		 -16°C
(4°F)		 -22°C
(-7°F)

Compare climate in Janesville with other places

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

Monthly average precipitation in Janesville, Wisconsin, United States §

Janesville usually has the most precipitation in May, June and October, with an average of 13 rainy days and 118 mm (4.6 inches) of precipitation per month.The driest months in Janesville are February, November and December. On average, 50 mm (2.0 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Janesville, Wisconsin, 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) 58 (2.3) 54 (2.1) 59 (2.3) 102 (4.0) 133 (5.3) 110 (4.3) 77 (3.0) 94 (3.7) 110 (4.3) 111 (4.4) 45 (1.8) 50 (2.0)
Average precipitation days (≥ 1 mm) 8 9 9 13 14 12 11 10 10 13 7 6

Monthly sunshine hours in Janesville, Wisconsin, United States §

The sunniest months in Janesville are June, July and August, when the sun shines an average of 11 hours 3 minutes a day.Least sunny months in Janesville: January, November and December receive an average of 5 hours 25 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Janesville, Wisconsin, 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 128 193 233 240 269 324 357 334 270 205 189 180
Mean daily daylight hours 9h 25m 10h 33m 11h 58m 13h 25m 14h 39m 15h 15m 14h 55m 13h 49m 12h 26m 10h 59m 9h 43m 9h 4m

Solar UV radiation in Janesville, Wisconsin, United States §

Janesville experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 9 - 10, which corresponds to the Very High category of sun exposure.January, November and December are in the Low / Moderate exposure category. In these months, the maximum values of the UV index do not exceed 3. For more detailed information, check out our hourly Janesville UV Index data.

Average daily maximum UV levels by month for Janesville, Wisconsin, 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 4 6 8 9 10 10 9 8 5 3 2