December weather forecastGrinnell, IA
December
Weather in December
The first month of the winter, December, is also an icy month in Grinnell, Iowa, with an average temperature fluctuating between 33.1°F (0.6°C) and 22.1°F (-5.5°C).Temperature
December shows a mild decline in the average high-temperature, falling from November's frosty 46.2°F (7.9°C) to a wintry 33.1°F (0.6°C). During the nights in December, Grinnell experiences a consistent average temperature of 22.1°F (-5.5°C).Humidity
In December, the average relative humidity is 80%.Rainfall
In December, the rain falls for 5.7 days. Throughout December, 0.51" (13mm) of precipitation is accumulated. In Grinnell, Iowa, during the entire year, the rain falls for 117.5 days and collects up to 13.03" (331mm) of precipitation.Snowfall
January through May, October through December are months with snowfall. In Grinnell, in December, snow falls for 6.9 days, with typically accumulated 0.79" (20mm) of snow. Throughout the year, there are 30.7 snowfall days, and 6.06" (154mm) of snow is accumulated.Daylight
December has the shortest days of the year in Grinnell, with an average of 9h and 12min of daylight.On the first day of December in Grinnell, sunrise is at 7:19 am and sunset at 4:41 pm. On the last day of the month, sunrise is at 7:37 am and sunset at 4:50 pm CST.
Sunshine
The average sunshine in December is 4.6h.UV index
In December, the average daily maximum UV index in Grinnell, Iowa, is 2. A UV Index estimate of 2, and below, represents a low health risk from exposure to the Sun's UV rays for ordinary individuals.Note: An average UV index of 2 in December transforms into this advice:
Sun exposure does not present considerable issues for many, yet infants, fair-skinned people, and children necessitate constant protection. For skin protection, it's recommended to minimize Sun exposure during its peak hours around midday. Tightly woven clothing, when worn loosely, shields effectively against the Sun. Heed this! Snow reflection can almost augment the UV radiation of the sun by double.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Grinnell, IA
- Average high temperature in December: 33.1°F
The warmest month (with the highest average high temperature) is July (81.1°F).
The month with the lowest average high temperature is January (27°F).
- Average low temperature in December: 22.1°F
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (13.8°F).
Average pressure in December
Grinnell, IA
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in December
Grinnell, IA
- Average wind speed in December: 10.1mph
The windiest month (with the highest average wind speed) is April (10.7mph).
The calmest month (with the lowest average wind speed) is August (7mph).
Average humidity in December
Grinnell, IA
- Average humidity in December: 80%
The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Grinnell, IA
- Average rainfall in December: 0.51"
The wettest months (with the highest rainfall) are May and June (1.97").
The driest month (with the least rainfall) is January (0.47").
Average rainfall days in December
Grinnell, IA
- Average rainfall days in December: 5.7 days
The month with the highest number of rainy days is June (15.1 days).
The month with the least rainy days is February (4.1 days).
Average snowfall in December
Grinnell, IA
- Average snowfall in December: 0.79"
The month with the highest snowfall is January (1.81").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Grinnell, IA
- Average snowfall days in December: 6.9 days
The month with the highest number of snowfall days is January (8.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Grinnell, IA
- Average daylight in December: 9h and 12min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in December: 4h and 36min
The month with the most sunshine is July (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).
Average sunshine days in December
Grinnell, IA
- Average sunshine days in December: 20.9 days
The month with the most sunshine days is January (21.1 days).
The month with the least sunshine days is June (11.5 days).
Average UV index in December
Grinnell, IA
- Average UV index in December: 2
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in December
Grinnell, IA
- Average cloud cover in December: 52
The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is September (Cloud cover 29).
Average visibility in December
Grinnell, IA
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).
