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Monthly climate in Denison, Iowa, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Denison 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 38 °C (100 °F).The average annual precipitation amounts to about 942 mm (37.1 inches) and receives 98 rainy days on the 1 mm (0.04 inches) threshold annually.Denison enjoys an average of 3040 hours of sunshine throughout the year, and daylight varies from 9 hours 9 minutes to 15 hours 10 minutes per day.

Monthly average temperatures in Denison, Iowa, United States §

The warmest months in Denison 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 -5 to -2 °C (23 - 29 °F) throughout the day. On average each year, Denison experiences 91 days above 25 °C (77.0 °F) and 126 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Denison, Iowa, 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
(68°F)		 25°C
(76°F)		 29°C
(85°F)		 35°C
(95°F)		 38°C
(100°F)		 34°C
(94°F)		 35°C
(96°F)		 35°C
(95°F)		 31°C
(88°F)		 25°C
(78°F)		 21°C
(70°F)
Mean maximum 10°C
(51°F)		 14°C
(58°F)		 21°C
(70°F)		 26°C
(79°F)		 32°C
(89°F)		 33°C
(92°F)		 34°C
(93°F)		 32°C
(90°F)		 33°C
(91°F)		 29°C
(85°F)		 19°C
(66°F)		 14°C
(58°F)
Average high -1°C
(31°F)		 0°C
(32°F)		 9°C
(48°F)		 15°C
(59°F)		 21°C
(70°F)		 28°C
(84°F)		 29°C
(85°F)		 28°C
(82°F)		 25°C
(78°F)		 16°C
(61°F)		 8°C
(47°F)		 3°C
(38°F)
Daily mean -5°C
(23°F)		 -5°C
(23°F)		 4°C
(39°F)		 9°C
(48°F)		 16°C
(61°F)		 23°C
(74°F)		 24°C
(76°F)		 23°C
(73°F)		 20°C
(68°F)		 10°C
(51°F)		 3°C
(38°F)		 -2°C
(29°F)
Average low -10°C
(15°F)		 -10°C
(14°F)		 -1°C
(30°F)		 3°C
(38°F)		 11°C
(52°F)		 18°C
(64°F)		 19°C
(67°F)		 17°C
(64°F)		 14°C
(58°F)		 5°C
(42°F)		 -2°C
(28°F)		 -6°C
(21°F)
Mean minimum -24°C
(-10°F)		 -23°C
(-9°F)		 -11°C
(12°F)		 -7°C
(20°F)		 3°C
(38°F)		 11°C
(52°F)		 13°C
(57°F)		 11°C
(52°F)		 6°C
(43°F)		 -4°C
(26°F)		 -11°C
(12°F)		 -16°C
(3°F)
Minimum -29°C
(-21°F)		 -33°C
(-27°F)		 -21°C
(-6°F)		 -12°C
(11°F)		 1°C
(35°F)		 8°C
(47°F)		 12°C
(53°F)		 10°C
(50°F)		 4°C
(40°F)		 -8°C
(18°F)		 -17°C
(2°F)		 -24°C
(-11°F)

Compare climate in Denison with other places

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

Monthly average precipitation in Denison, Iowa, United States §

Denison usually has the most precipitation in May, August and October, with an average of 11 rainy days and 130 mm (5.1 inches) of precipitation per month.The driest months in Denison are January, November and December. On average, 32 mm (1.3 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Denison, Iowa, 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) 27 (1.1) 39 (1.5) 79 (3.1) 66 (2.6) 161 (6.3) 105 (4.1) 65 (2.6) 112 (4.4) 100 (3.9) 117 (4.6) 32 (1.3) 38 (1.5)
Average precipitation days (≥ 1 mm) 5 7 8 10 15 10 7 8 9 10 5 4

Monthly sunshine hours in Denison, Iowa, United States §

The sunniest months in Denison are June, July and August, when the sun shines an average of 11 hours 21 minutes a day.Least sunny months in Denison: January, February and November receive an average of 6 hours 7 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Denison, Iowa, 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 144 196 217 255 257 345 373 325 275 225 210 212
Mean daily daylight hours 9h 30m 10h 35m 11h 58m 13h 23m 14h 34m 15h 10m 14h 50m 13h 46m 12h 25m 11h 1m 9h 47m 9h 9m

Solar UV radiation in Denison, Iowa, United States §

Denison 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 Denison UV Index data.

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