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Monthly climate in Ottawa, Illinois, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Ottawa features a humid continental climate (Dfa).Temperatures typically range between -3 °C (26 °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 (96 °F).The average annual precipitation amounts to about 1174 mm (46.2 inches) and receives 130 rainy days on the 1 mm (0.04 inches) threshold annually.Ottawa enjoys an average of 2939 hours of sunshine throughout the year, and daylight varies from 9 hours 14 minutes to 15 hours 5 minutes per day.

Monthly average temperatures in Ottawa, Illinois, United States §

The warmest months in Ottawa are June, July and August, with daily mean temperatures ranging from 23 to 24 °C (73 - 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 (26 - 34 °F) throughout the day. On average each year, Ottawa experiences 97 days above 25 °C (77.0 °F) and 107 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Ottawa, 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 15°C
(59°F)		 22°C
(73°F)		 26°C
(79°F)		 29°C
(85°F)		 34°C
(94°F)		 35°C
(95°F)		 34°C
(93°F)		 35°C
(96°F)		 35°C
(95°F)		 32°C
(89°F)		 25°C
(77°F)		 20°C
(68°F)
Mean maximum 11°C
(53°F)		 15°C
(60°F)		 21°C
(70°F)		 27°C
(82°F)		 31°C
(89°F)		 33°C
(92°F)		 33°C
(92°F)		 33°C
(91°F)		 32°C
(91°F)		 30°C
(86°F)		 18°C
(65°F)		 17°C
(62°F)
Average high 0°C
(33°F)		 2°C
(36°F)		 10°C
(50°F)		 15°C
(60°F)		 22°C
(72°F)		 28°C
(82°F)		 29°C
(84°F)		 28°C
(83°F)		 26°C
(79°F)		 18°C
(65°F)		 9°C
(48°F)		 5°C
(42°F)
Daily mean -3°C
(26°F)		 -2°C
(28°F)		 5°C
(41°F)		 10°C
(50°F)		 17°C
(63°F)		 23°C
(73°F)		 24°C
(76°F)		 23°C
(74°F)		 20°C
(69°F)		 13°C
(56°F)		 4°C
(40°F)		 1°C
(34°F)
Average low -7°C
(19°F)		 -7°C
(20°F)		 -0°C
(32°F)		 5°C
(41°F)		 12°C
(54°F)		 18°C
(64°F)		 20°C
(68°F)		 18°C
(64°F)		 15°C
(59°F)		 8°C
(47°F)		 -0°C
(32°F)		 -3°C
(26°F)
Mean minimum -22°C
(-7°F)		 -22°C
(-7°F)		 -11°C
(13°F)		 -4°C
(25°F)		 3°C
(39°F)		 13°C
(55°F)		 14°C
(58°F)		 12°C
(54°F)		 7°C
(45°F)		 -1°C
(31°F)		 -10°C
(14°F)		 -13°C
(8°F)
Minimum -31°C
(-24°F)		 -33°C
(-27°F)		 -19°C
(-2°F)		 -8°C
(17°F)		 -1°C
(31°F)		 10°C
(49°F)		 14°C
(57°F)		 11°C
(52°F)		 4°C
(39°F)		 -5°C
(24°F)		 -14°C
(6°F)		 -21°C
(-6°F)

Compare climate in Ottawa with other places

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

Monthly average precipitation in Ottawa, Illinois, United States §

Ottawa usually has the most precipitation in May, June and October, with an average of 13 rainy days and 148 mm (5.8 inches) of precipitation per month.The driest months in Ottawa are January, November and December. On average, 58 mm (2.3 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Ottawa, 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) 62 (2.5) 66 (2.6) 93 (3.7) 117 (4.6) 165 (6.5) 145 (5.7) 101 (4.0) 87 (3.4) 91 (3.6) 134 (5.3) 57 (2.2) 55 (2.2)
Average precipitation days (≥ 1 mm) 8 11 11 13 16 13 12 11 9 12 8 6

Monthly sunshine hours in Ottawa, Illinois, United States §

The sunniest months in Ottawa are June, July and August, when the sun shines an average of 11 hours 1 minutes a day.Least sunny months in Ottawa: January, February and December receive an average of 5 hours 22 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Ottawa, 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 120 177 224 237 276 331 350 332 282 220 194 191
Mean daily daylight hours 9h 34m 10h 37m 11h 58m 13h 20m 14h 30m 15h 5m 14h 46m 13h 44m 12h 24m 11h 2m 9h 50m 9h 14m

Solar UV radiation in Ottawa, Illinois, United States §

Ottawa 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 4. For more detailed information, check out our hourly Ottawa UV Index data.

Average daily maximum UV levels by month for Ottawa, 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 8 9 10 10 9 8 6 4 2