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Monthly climate in Harrisburg, Illinois, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Harrisburg features a humid subtropical climate (Cfa).Temperatures typically range between 2 °C (36 °F) and 27 °C (80 °F) through the year, but rarely can drop to -18 °C (-1 °F) or can rise to as high as 37 °C (99 °F).The average annual precipitation amounts to about 1276 mm (50.2 inches) and receives 122 rainy days on the 1 mm (0.04 inches) threshold annually.Harrisburg enjoys an average of 2980 hours of sunshine throughout the year, and daylight varies from 9 hours 34 minutes to 14 hours 43 minutes per day.

Monthly average temperatures in Harrisburg, Illinois, United States §

The warmest months in Harrisburg are June, July and August, with daily mean temperatures ranging from 25 to 27 °C (77 - 80 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 2 to 5 °C (36 - 42 °F) throughout the day. On average each year, Harrisburg experiences 128 days above 25 °C (77.0 °F) and 61 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Harrisburg, 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 22°C
(71°F)		 24°C
(75°F)		 26°C
(80°F)		 31°C
(87°F)		 33°C
(92°F)		 36°C
(97°F)		 37°C
(99°F)		 36°C
(97°F)		 35°C
(95°F)		 35°C
(95°F)		 27°C
(80°F)		 23°C
(73°F)
Mean maximum 18°C
(64°F)		 20°C
(69°F)		 24°C
(76°F)		 29°C
(84°F)		 32°C
(90°F)		 34°C
(94°F)		 35°C
(95°F)		 35°C
(95°F)		 33°C
(92°F)		 32°C
(89°F)		 23°C
(73°F)		 20°C
(68°F)
Average high 6°C
(43°F)		 9°C
(48°F)		 15°C
(59°F)		 19°C
(67°F)		 25°C
(77°F)		 30°C
(86°F)		 31°C
(89°F)		 30°C
(86°F)		 28°C
(84°F)		 22°C
(71°F)		 13°C
(55°F)		 10°C
(51°F)
Daily mean 2°C
(36°F)		 4°C
(39°F)		 9°C
(49°F)		 14°C
(57°F)		 20°C
(69°F)		 25°C
(77°F)		 27°C
(80°F)		 25°C
(78°F)		 23°C
(74°F)		 16°C
(61°F)		 8°C
(46°F)		 5°C
(42°F)
Average low -2°C
(29°F)		 -1°C
(31°F)		 5°C
(40°F)		 9°C
(48°F)		 16°C
(60°F)		 20°C
(69°F)		 22°C
(73°F)		 20°C
(69°F)		 18°C
(64°F)		 11°C
(52°F)		 2°C
(37°F)		 1°C
(34°F)
Mean minimum -13°C
(9°F)		 -13°C
(9°F)		 -6°C
(21°F)		 -0°C
(32°F)		 6°C
(43°F)		 15°C
(60°F)		 18°C
(64°F)		 14°C
(58°F)		 9°C
(49°F)		 2°C
(35°F)		 -6°C
(21°F)		 -9°C
(17°F)
Minimum -17°C
(1°F)		 -18°C
(-1°F)		 -12°C
(11°F)		 -3°C
(27°F)		 4°C
(39°F)		 11°C
(53°F)		 16°C
(61°F)		 13°C
(55°F)		 8°C
(47°F)		 -2°C
(29°F)		 -11°C
(12°F)		 -15°C
(6°F)

Compare climate in Harrisburg with other places

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

Monthly average precipitation in Harrisburg, Illinois, United States §

Harrisburg usually has the most precipitation in March, April and May, with an average of 12 rainy days and 133 mm (5.2 inches) of precipitation per month.The driest months in Harrisburg are August, September and December. On average, 84 mm (3.3 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Harrisburg, 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) 96 (3.8) 115 (4.5) 137 (5.4) 134 (5.3) 128 (5.0) 120 (4.7) 91 (3.6) 84 (3.3) 79 (3.1) 114 (4.5) 90 (3.5) 88 (3.5)
Average precipitation days (≥ 1 mm) 8 11 13 12 13 11 10 10 8 9 9 8

Monthly sunshine hours in Harrisburg, Illinois, United States §

The sunniest months in Harrisburg are June, July and August, when the sun shines an average of 10 hours 52 minutes a day.Least sunny months in Harrisburg: January, February and December receive an average of 5 hours 19 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Harrisburg, 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 128 168 204 255 288 328 351 319 289 244 213 187
Mean daily daylight hours 9h 52m 10h 47m 11h 59m 13h 11m 14h 13m 14h 43m 14h 27m 13h 32m 12h 22m 11h 9m 10h 6m 9h 34m

Solar UV radiation in Harrisburg, Illinois, United States §

Harrisburg experiences the highest level of ultraviolet (UV) radiation in April, May and June, 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 5. For more detailed information, check out our hourly Harrisburg UV Index data.

Average daily maximum UV levels by month for Harrisburg, 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 6 7 10 11 11 10 10 9 7 5 3