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Monthly climate in Forreston, Illinois, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Forreston features a humid continental climate (Dfa).Temperatures typically range between -5 °C (23 °F) and 24 °C (76 °F) through the year, but rarely can drop to -33 °C (-27 °F) or can rise to as high as 35 °C (95 °F).The average annual precipitation amounts to about 1056 mm (41.6 inches) and receives 121 rainy days on the 1 mm (0.04 inches) threshold annually.Forreston enjoys an average of 2937 hours of sunshine throughout the year, and daylight varies from 9 hours 8 minutes to 15 hours 11 minutes per day.

Monthly average temperatures in Forreston, Illinois, United States §

The warmest months in Forreston 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 -5 to -1 °C (23 - 31 °F) throughout the day. On average each year, Forreston experiences 84 days above 25 °C (77.0 °F) and 120 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Forreston, 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 12°C
(54°F)		 20°C
(69°F)		 23°C
(74°F)		 27°C
(81°F)		 34°C
(93°F)		 35°C
(95°F)		 34°C
(93°F)		 34°C
(93°F)		 33°C
(92°F)		 31°C
(89°F)		 23°C
(74°F)		 19°C
(67°F)
Mean maximum 9°C
(48°F)		 12°C
(55°F)		 19°C
(67°F)		 25°C
(78°F)		 30°C
(87°F)		 32°C
(90°F)		 33°C
(92°F)		 32°C
(90°F)		 31°C
(89°F)		 29°C
(84°F)		 17°C
(64°F)		 15°C
(59°F)
Average high -2°C
(29°F)		 0°C
(33°F)		 8°C
(47°F)		 13°C
(57°F)		 21°C
(70°F)		 27°C
(81°F)		 29°C
(84°F)		 27°C
(82°F)		 25°C
(76°F)		 16°C
(62°F)		 7°C
(45°F)		 3°C
(38°F)
Daily mean -5°C
(23°F)		 -4°C
(25°F)		 3°C
(38°F)		 9°C
(48°F)		 16°C
(61°F)		 22°C
(72°F)		 24°C
(76°F)		 22°C
(72°F)		 19°C
(67°F)		 11°C
(53°F)		 3°C
(38°F)		 -1°C
(31°F)
Average low -9°C
(16°F)		 -9°C
(16°F)		 -1°C
(30°F)		 3°C
(39°F)		 11°C
(52°F)		 17°C
(63°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)		 -23°C
(-9°F)		 -13°C
(10°F)		 -5°C
(24°F)		 2°C
(36°F)		 12°C
(54°F)		 14°C
(57°F)		 12°C
(54°F)		 6°C
(43°F)		 -2°C
(28°F)		 -11°C
(13°F)		 -14°C
(7°F)
Minimum -32°C
(-25°F)		 -33°C
(-27°F)		 -22°C
(-7°F)		 -8°C
(18°F)		 -2°C
(29°F)		 9°C
(49°F)		 12°C
(54°F)		 11°C
(51°F)		 2°C
(36°F)		 -6°C
(22°F)		 -17°C
(2°F)		 -21°C
(-6°F)

Compare climate in Forreston with other places

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

Monthly average precipitation in Forreston, Illinois, United States §

Forreston usually has the most precipitation in May, June and September, with an average of 12 rainy days and 130 mm (5.1 inches) of precipitation per month.The driest months in Forreston are February, November and December. On average, 51 mm (2.0 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Forreston, 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) 59 (2.3) 57 (2.2) 72 (2.8) 102 (4.0) 150 (5.9) 118 (4.7) 80 (3.2) 87 (3.4) 122 (4.8) 111 (4.4) 46 (1.8) 50 (2.0)
Average precipitation days (≥ 1 mm) 7 9 10 12 15 12 11 9 10 13 7 6

Monthly sunshine hours in Forreston, Illinois, United States §

The sunniest months in Forreston are June, July and August, when the sun shines an average of 11 hours 2 minutes a day.Least sunny months in Forreston: January, February and December receive an average of 5 hours 34 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Forreston, 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 130 192 231 240 267 325 358 331 273 208 192 184
Mean daily daylight hours 9h 29m 10h 35m 11h 58m 13h 23m 14h 35m 15h 11m 14h 51m 13h 47m 12h 25m 11h 0m 9h 46m 9h 8m

Solar UV radiation in Forreston, Illinois, United States §

Forreston 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 Forreston UV Index data.

Average daily maximum UV levels by month for Forreston, 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 5 3 2