December weather forecastPortsmouth, IA
December
Weather in December
The first month of the winter, December, is also an icy month in Portsmouth, Iowa, with an average temperature varying between 20.8°F (-6.2°C) and 32.2°F (0.1°C).Temperature
The arrival of December corresponds with a shift in temperature, down from a frosty 46.2°F (7.9°C) in November to a cold 32.2°F (0.1°C). During December, an average low-temperature of 20.8°F (-6.2°C) is observed.Humidity
In Portsmouth, the average relative humidity in December is 79%.Rainfall
In Portsmouth, in December, during 4.2 rainfall days, 0.71" (18mm) of precipitation is typically accumulated. In Portsmouth, during the entire year, the rain falls for 113.5 days and collects up to 15.71" (399mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. In Portsmouth, in December, during 6.1 snowfall days, 1.06" (27mm) of snow is typically accumulated. In Portsmouth, during the entire year, snow falls for 31.5 days and aggregates up to 7.13" (181mm) of snow.Daylight
December has the shortest days of the year, with an average of 9h and 12min of daylight.On the first day of December, sunrise is at 7:30 am and sunset at 4:52 pm. On the last day of the month, sunrise is at 7:48 am and sunset at 5:01 pm CST.
Sunshine
In December, the average sunshine is 4.8h.UV index
The months with the lowest UV index are January, February, October through December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV radiation for the average person.Note: In December, the average maximum UV index of 2 translates into the following recommendations:
Extended time in the sun generally does not harm most, but those with sensitive skin, infants, and children should always be protected. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. Employ a wide-brim hat for potent defense against up to 50% of UV rays. Mind you! Snow reflection can increase the intensity of the Sun's UV radiation nearly twofold.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Portsmouth, IA
- Average high temperature in December: 32.2°F
The warmest month (with the highest average high temperature) is July (82.6°F).
The month with the lowest average high temperature is January (27.3°F).
- Average low temperature in December: 20.8°F
The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (14.5°F).
Average pressure in December
Portsmouth, IA
- Average pressure in December: 30.13"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.87"Hg).
Average wind speed in December
Portsmouth, IA
- Average wind speed in December: 10.1mph
The windiest month (with the highest average wind speed) is April (10.9mph).
The calmest month (with the lowest average wind speed) is July (7.2mph).
Average humidity in December
Portsmouth, IA
- Average humidity in December: 79%
The month with the highest relative humidity is January (83%).
The month with the lowest relative humidity is October (68%).
Average rainfall in December
Portsmouth, IA
- Average rainfall in December: 0.71"
The wettest month (with the highest rainfall) is June (2.64").
The driest month (with the least rainfall) is January (0.43").
Average rainfall days in December
Portsmouth, IA
- Average rainfall days in December: 4.2 days
The month with the highest number of rainy days is June (16.1 days).
The month with the least rainy days is February (2.8 days).
Average snowfall in December
Portsmouth, IA
- Average snowfall in December: 1.06"
The month with the highest snowfall is February (2.09").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Portsmouth, IA
- Average snowfall days in December: 6.1 days
The month with the highest number of snowfall days is January (8.3 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Portsmouth, IA
- Average daylight in December: 9h and 12min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in December: 4h and 48min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).
Average sunshine days in December
Portsmouth, IA
- Average sunshine days in December: 21.6 days
The month with the most sunshine days is December (21.6 days).
The month with the least sunshine days is June (11.4 days).
Average UV index in December
Portsmouth, IA
- Average UV index in December: 2
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, October, November and December (UV index 2).
Average cloud cover in December
Portsmouth, IA
- Average cloud cover in December: 48
The month with the most cloud cover is January (Cloud cover 52).
The month with the least cloud cover is July (Cloud cover 27).
Average visibility in December
Portsmouth, IA
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
