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Monthly climate in Grinnell, Iowa, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Grinnell features a humid continental climate (Dfa).Temperatures typically range between -6 °C (22 °F) and 24 °C (76 °F) through the year, but rarely can drop to -32 °C (-25 °F) or can rise to as high as 37 °C (98 °F).The average annual precipitation amounts to about 1049 mm (41.3 inches) and receives 108 rainy days on the 1 mm (0.04 inches) threshold annually.Grinnell enjoys an average of 3032 hours of sunshine throughout the year, and daylight varies from 9 hours 11 minutes to 15 hours 8 minutes per day.

Monthly average temperatures in Grinnell, Iowa, United States §

The warmest months in Grinnell 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 -6 to -1 °C (22 - 31 °F) throughout the day. On average each year, Grinnell experiences 93 days above 25 °C (77.0 °F) and 122 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Grinnell, 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 14°C
(57°F)		 22°C
(71°F)		 22°C
(73°F)		 29°C
(85°F)		 35°C
(95°F)		 37°C
(98°F)		 34°C
(94°F)		 34°C
(94°F)		 33°C
(92°F)		 31°C
(88°F)		 24°C
(75°F)		 23°C
(73°F)
Mean maximum 10°C
(50°F)		 14°C
(58°F)		 20°C
(68°F)		 26°C
(80°F)		 32°C
(90°F)		 33°C
(92°F)		 33°C
(93°F)		 32°C
(91°F)		 32°C
(90°F)		 30°C
(86°F)		 19°C
(66°F)		 17°C
(62°F)
Average high -2°C
(30°F)		 -0°C
(32°F)		 9°C
(48°F)		 15°C
(59°F)		 22°C
(71°F)		 28°C
(83°F)		 29°C
(85°F)		 28°C
(82°F)		 25°C
(78°F)		 16°C
(62°F)		 8°C
(47°F)		 4°C
(39°F)
Daily mean -6°C
(22°F)		 -5°C
(23°F)		 4°C
(39°F)		 9°C
(49°F)		 17°C
(62°F)		 23°C
(74°F)		 24°C
(76°F)		 23°C
(73°F)		 20°C
(68°F)		 11°C
(53°F)		 3°C
(38°F)		 -1°C
(31°F)
Average low -10°C
(14°F)		 -10°C
(15°F)		 -1°C
(31°F)		 4°C
(39°F)		 12°C
(53°F)		 18°C
(64°F)		 19°C
(67°F)		 17°C
(63°F)		 14°C
(58°F)		 7°C
(44°F)		 -2°C
(29°F)		 -5°C
(23°F)
Mean minimum -24°C
(-12°F)		 -24°C
(-10°F)		 -13°C
(9°F)		 -6°C
(21°F)		 4°C
(39°F)		 12°C
(53°F)		 15°C
(59°F)		 12°C
(53°F)		 7°C
(44°F)		 -3°C
(26°F)		 -11°C
(12°F)		 -15°C
(4°F)
Minimum -31°C
(-24°F)		 -32°C
(-25°F)		 -22°C
(-7°F)		 -10°C
(14°F)		 -0°C
(32°F)		 9°C
(48°F)		 13°C
(56°F)		 11°C
(51°F)		 4°C
(39°F)		 -6°C
(22°F)		 -17°C
(1°F)		 -23°C
(-8°F)

Compare climate in Grinnell with other places

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

Monthly average precipitation in Grinnell, Iowa, United States §

Grinnell usually has the most precipitation in May, June and October, with an average of 12 rainy days and 148 mm (5.8 inches) of precipitation per month.The driest months in Grinnell are January, November and December. On average, 42 mm (1.7 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Grinnell, 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) 43 (1.7) 48 (1.9) 79 (3.1) 81 (3.2) 166 (6.5) 133 (5.2) 81 (3.2) 71 (2.8) 118 (4.7) 145 (5.7) 46 (1.8) 38 (1.5)
Average precipitation days (≥ 1 mm) 6 8 9 10 15 10 9 9 9 12 6 5

Monthly sunshine hours in Grinnell, Iowa, United States §

The sunniest months in Grinnell are June, July and August, when the sun shines an average of 11 hours 25 minutes a day.Least sunny months in Grinnell: January, February and December receive an average of 5 hours 49 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Grinnell, 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 135 189 223 253 263 341 372 336 277 225 207 205
Mean daily daylight hours 9h 31m 10h 36m 11h 58m 13h 22m 14h 33m 15h 8m 14h 49m 13h 45m 12h 25m 11h 1m 9h 48m 9h 11m

Solar UV radiation in Grinnell, Iowa, United States §

Grinnell experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 9 - 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 4. For more detailed information, check out our hourly Grinnell UV Index data.

Average daily maximum UV levels by month for Grinnell, 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 9 11 10 9 8 6 4 3