Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
Observing a mild shift, the average high-temperature during December reduces from November's frosty 45.9°F (7.7°C) to a cold 32°F (0°C). An average low-temperature of 21°F (-6.1°C) is observed during December nights in Herndon, Iowa.Humidity
In December, the average relative humidity is 80%.Rainfall
In Herndon, in December, it is raining for 4.8 days, with typically 1.34" (34mm) of accumulated precipitation. In Herndon, during the entire year, the rain falls for 125.7 days and collects up to 26.5" (673mm) of precipitation.Snowfall
Months with snowfall in Herndon, Iowa, are January through May, October through December. In December, in Herndon, it is snowing for 8.3 days. Throughout December, 2.64" (67mm) of snow is accumulated. In Herndon, during the entire year, snow falls for 38.1 days and aggregates up to 15.31" (389mm) of snow.Daylight
With an average of 9h and 12min of daylight, December has the shortest days of the year.On the first day of the month, sunrise is at 7:26 am and sunset at 4:47 pm. On the last day of December, sunrise is at 7:44 am and sunset at 4:56 pm CST.
Sunshine
In Herndon, the average sunshine in December is 4.7h.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 value of 2, and less, symbolizes a minimal health hazard from exposure to the Sun's UV rays for the ordinary person.Note: In December, the UV index of 2 transforms into the following advice:
Sun exposure does not present considerable issues for many, yet infants, fair-skinned people, and children necessitate constant protection. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays. Consider carefully! The reflective quality of snow can almost double the intensity of the Sun's UV radiation.
Frequently asked questions
How cold is it in Herndon in December?
What is the average humidity in December in Herndon?
How many days does it rain in December in Herndon?
How many days does it snow in December in Herndon?
What is the month with the shortest days in Herndon?
What is the average length of the day in December in Herndon?
What time are sunrise and sunset in December in Herndon?
How long on average sun shines in December in Herndon?
What are the months with the lowest UV index in Herndon?
What is the UV index reading in December in Herndon?
Average temperature in December
Herndon, IA
- Average high temperature in December: 32°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (26.8°F).
- Average low temperature in December: 21°F
The month with the highest average low temperature is July (64.6°F).
The coldest month (with the lowest average low temperature) is January (13.5°F).
Average pressure in December
Herndon, IA
- Average pressure in December: 30.12"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in December
Herndon, IA
- Average wind speed in December: 10.2mph
The windiest month (with the highest average wind speed) is April (10.7mph).
The calmest months (with the lowest average wind speed) are July and August (7.1mph).
Average humidity in December
Herndon, 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 (69%).
Average rainfall in December
Herndon, IA
- Average rainfall in December: 1.34"
The wettest month (with the highest rainfall) is May (4.06").
The driest month (with the least rainfall) is January (0.87").
Average rainfall days in December
Herndon, IA
- Average rainfall days in December: 4.8 days
The month with the highest number of rainy days is June (17.3 days).
The month with the least rainy days is February (3.4 days).
Average snowfall in December
Herndon, IA
- Average snowfall in December: 2.64"
The month with the highest snowfall is January (4.29").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Herndon, IA
- Average snowfall days in December: 8.3 days
The month with the highest number of snowfall days is January (9.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Herndon, IA
- Average daylight in December: 9h and 1min
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 4min
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 12min).
Average sunshine days in December
Herndon, IA
- Average sunshine days in December: 18.8 days
The month with the most sunshine days is November (19.4 days).
The month with the least sunshine days is June (11.1 days).
Average UV index in December
Herndon, IA
- Average UV index in December: 2
The months with the highest UV index are June and July (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
Herndon, IA
- Average cloud cover in December: 50
The month with the most cloud cover is January (Cloud cover 55).
The months with the least cloud cover are July and September (Cloud cover 30).
Average visibility in December
Herndon, IA
- Average visibility in December: 6mi
The months with the highest visibility are February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, July and August (5mi).
Herndon, Iowa, USA
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