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Monthly climate in Joliet, Illinois, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Joliet features a humid continental climate (Dfa).Temperatures typically range between -3 °C (27 °F) and 24 °C (76 °F) through the year, but rarely can drop to -32 °C (-26 °F) or can rise to as high as 34 °C (94 °F).The average annual precipitation amounts to about 1184 mm (46.6 inches) and receives 130 rainy days on the 1 mm (0.04 inches) threshold annually.Joliet enjoys an average of 2984 hours of sunshine throughout the year, and daylight varies from 9 hours 12 minutes to 15 hours 7 minutes per day.

Monthly average temperatures in Joliet, Illinois, United States §

The warmest months in Joliet are June, July and August, with daily mean temperatures ranging from 22 to 24 °C (72 - 76 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from -3 to 1 °C (27 - 34 °F) throughout the day. On average each year, Joliet experiences 90 days above 25 °C (77.0 °F) and 105 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Joliet, Illinois, 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 16°C
(61°F)		 21°C
(70°F)		 26°C
(80°F)		 29°C
(85°F)		 34°C
(94°F)		 34°C
(94°F)		 34°C
(94°F)		 34°C
(93°F)		 34°C
(94°F)		 31°C
(89°F)		 25°C
(76°F)		 19°C
(67°F)
Mean maximum 11°C
(53°F)		 15°C
(59°F)		 21°C
(70°F)		 27°C
(81°F)		 31°C
(88°F)		 33°C
(91°F)		 33°C
(91°F)		 33°C
(91°F)		 32°C
(90°F)		 29°C
(85°F)		 18°C
(65°F)		 16°C
(61°F)
Average high 0°C
(33°F)		 2°C
(36°F)		 9°C
(49°F)		 15°C
(59°F)		 21°C
(71°F)		 27°C
(81°F)		 29°C
(84°F)		 28°C
(82°F)		 25°C
(78°F)		 18°C
(64°F)		 8°C
(47°F)		 5°C
(41°F)
Daily mean -3°C
(27°F)		 -2°C
(29°F)		 4°C
(40°F)		 9°C
(49°F)		 16°C
(62°F)		 22°C
(72°F)		 24°C
(76°F)		 23°C
(74°F)		 20°C
(68°F)		 13°C
(55°F)		 4°C
(40°F)		 1°C
(34°F)
Average low -7°C
(20°F)		 -7°C
(20°F)		 -0°C
(32°F)		 5°C
(40°F)		 12°C
(53°F)		 17°C
(63°F)		 20°C
(68°F)		 18°C
(65°F)		 15°C
(59°F)		 8°C
(47°F)		 -0°C
(32°F)		 -3°C
(27°F)
Mean minimum -22°C
(-7°F)		 -21°C
(-6°F)		 -10°C
(14°F)		 -4°C
(25°F)		 3°C
(37°F)		 13°C
(55°F)		 14°C
(58°F)		 12°C
(54°F)		 7°C
(45°F)		 -0°C
(32°F)		 -9°C
(16°F)		 -13°C
(9°F)
Minimum -31°C
(-23°F)		 -32°C
(-26°F)		 -19°C
(-2°F)		 -8°C
(19°F)		 -2°C
(29°F)		 10°C
(50°F)		 13°C
(56°F)		 10°C
(51°F)		 3°C
(39°F)		 -4°C
(26°F)		 -14°C
(6°F)		 -21°C
(-5°F)

Compare climate in Joliet with other places

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

Monthly average precipitation in Joliet, Illinois, United States §

Joliet usually has the most precipitation in May, June and October, with an average of 13 rainy days and 147 mm (5.8 inches) of precipitation per month.The driest months in Joliet are January, November and December. On average, 60 mm (2.4 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Joliet, Illinois, 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) 65 (2.6) 67 (2.6) 93 (3.7) 122 (4.8) 159 (6.3) 143 (5.6) 114 (4.5) 86 (3.4) 81 (3.2) 138 (5.4) 61 (2.4) 56 (2.2)
Average precipitation days (≥ 1 mm) 8 11 11 13 15 13 12 11 9 12 8 7

Monthly sunshine hours in Joliet, Illinois, United States §

The sunniest months in Joliet are June, July and August, when the sun shines an average of 11 hours 11 minutes a day.Least sunny months in Joliet: January, February and December receive an average of 5 hours 17 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Joliet, Illinois, 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 118 179 231 248 289 331 360 338 286 225 193 183
Mean daily daylight hours 9h 32m 10h 36m 11h 58m 13h 21m 14h 32m 15h 7m 14h 48m 13h 45m 12h 25m 11h 2m 9h 49m 9h 12m

Solar UV radiation in Joliet, Illinois, United States §

Joliet 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, February and December are in the Low / 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 Joliet UV Index data.

Average daily maximum UV levels by month for Joliet, Illinois, 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 6 4 2