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Monthly climate in Potomac, Illinois, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Potomac features a humid continental climate (Dfa).Temperatures typically range between -2 °C (29 °F) and 25 °C (77 °F) through the year, but rarely can drop to -28 °C (-17 °F) or can rise to as high as 36 °C (97 °F).The average annual precipitation amounts to about 1166 mm (45.9 inches) and receives 125 rainy days on the 1 mm (0.04 inches) threshold annually.Potomac enjoys an average of 2926 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 Potomac, Illinois, United States §

The warmest months in Potomac are June, July and August, with daily mean temperatures ranging from 23 to 25 °C (74 - 77 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from -2 to 2 °C (29 - 36 °F) throughout the day. On average each year, Potomac experiences 108 days above 25 °C (77.0 °F) and 96 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Potomac, 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 18°C
(65°F)		 22°C
(71°F)		 26°C
(79°F)		 29°C
(85°F)		 34°C
(94°F)		 35°C
(95°F)		 36°C
(97°F)		 34°C
(93°F)		 34°C
(93°F)		 33°C
(91°F)		 25°C
(78°F)		 18°C
(65°F)
Mean maximum 14°C
(58°F)		 17°C
(62°F)		 21°C
(71°F)		 27°C
(81°F)		 31°C
(89°F)		 33°C
(92°F)		 34°C
(93°F)		 33°C
(91°F)		 32°C
(91°F)		 30°C
(86°F)		 20°C
(68°F)		 17°C
(62°F)
Average high 2°C
(36°F)		 4°C
(40°F)		 11°C
(52°F)		 16°C
(62°F)		 23°C
(74°F)		 28°C
(83°F)		 30°C
(86°F)		 28°C
(83°F)		 27°C
(80°F)		 19°C
(67°F)		 10°C
(50°F)		 7°C
(44°F)
Daily mean -2°C
(29°F)		 -1°C
(31°F)		 6°C
(43°F)		 11°C
(52°F)		 18°C
(65°F)		 23°C
(74°F)		 25°C
(77°F)		 23°C
(74°F)		 21°C
(70°F)		 14°C
(57°F)		 5°C
(41°F)		 2°C
(36°F)
Average low -6°C
(22°F)		 -5°C
(23°F)		 1°C
(34°F)		 6°C
(43°F)		 13°C
(56°F)		 18°C
(65°F)		 20°C
(69°F)		 18°C
(65°F)		 16°C
(60°F)		 9°C
(48°F)		 0°C
(33°F)		 -3°C
(28°F)
Mean minimum -20°C
(-4°F)		 -18°C
(-0°F)		 -10°C
(14°F)		 -3°C
(26°F)		 3°C
(38°F)		 13°C
(56°F)		 14°C
(58°F)		 13°C
(55°F)		 8°C
(47°F)		 -0°C
(32°F)		 -8°C
(18°F)		 -14°C
(7°F)
Minimum -28°C
(-17°F)		 -22°C
(-8°F)		 -18°C
(0°F)		 -7°C
(20°F)		 -1°C
(31°F)		 10°C
(50°F)		 13°C
(55°F)		 12°C
(54°F)		 6°C
(42°F)		 -4°C
(25°F)		 -13°C
(9°F)		 -25°C
(-12°F)

Compare climate in Potomac with other places

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

Monthly average precipitation in Potomac, Illinois, United States §

Potomac usually has the most precipitation in April, May and October, with an average of 12 rainy days and 128 mm (5.0 inches) of precipitation per month.The driest months in Potomac are September, November and December. On average, 70 mm (2.7 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Potomac, 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) 77 (3.0) 77 (3.0) 111 (4.4) 118 (4.6) 147 (5.8) 112 (4.4) 87 (3.4) 110 (4.3) 76 (3.0) 119 (4.7) 74 (2.9) 59 (2.3)
Average precipitation days (≥ 1 mm) 8 10 11 11 15 12 12 11 7 11 9 8

Monthly sunshine hours in Potomac, Illinois, United States §

The sunniest months in Potomac are June, July and August, when the sun shines an average of 11 hours 2 minutes a day.Least sunny months in Potomac: January, February and December receive an average of 5 hours 4 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Potomac, 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 114 167 221 240 282 331 352 331 289 226 189 180
Mean daily daylight hours 9h 39m 10h 40m 11h 58m 13h 18m 14h 25m 14h 59m 14h 40m 13h 40m 12h 24m 11h 4m 9h 55m 9h 20m

Solar UV radiation in Potomac, Illinois, United States §

Potomac experiences the highest level of ultraviolet (UV) radiation in May, June and July, 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 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 Potomac UV Index data.

Average daily maximum UV levels by month for Potomac, 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 5 6 9 10 11 10 9 8 6 4 2