December weather forecastBoulder, CO
December
Weather in December
December in Boulder signs off the calendar year with full blown winter. The city welcomes stringent cold, with frequent encounters of snowfall amounting up to approximately 3.94" (100mm). Temperatures plunge to their yearly lows in line with the season, with daylight hours reaching a dwindling stage. However, despite the chilly conditions, plentiful sunlight promises to brighten up the winter days. Thus, December embodies the epitome of winter weather in Boulder, concluding the year on a frosty note.Temperature
Boulder experiences its lowest temperatures in December, with an average peak of 35.2°F (1.8°C) and a low of 18.1°F (-7.7°C).Humidity
In Boulder, the average relative humidity in December is 65%.Rainfall
In Boulder, in December, during 3.9 rainfall days, 0.51" (13mm) of precipitation is typically accumulated. In Boulder, during the entire year, the rain falls for 117.3 days and collects up to 14.17" (360mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. In Boulder, during December, snow falls for 7.2 days and regularly aggregates up to 3.94" (100mm) of snow. In Boulder, during the entire year, snow falls for 44.8 days and aggregates up to 37.01" (940mm) of snow.Daylight
The month with the shortest days is December, with an average of 9h and 24min of daylight.On the first day of December, sunrise is at 7:04 am and sunset at 4:36 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 4:46 pm MST.
Sunshine
In Boulder, the average sunshine in December is 6.8h.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.Note: The daily maximum UV index of 2 in December interprets into the following advice:
Prolonged sun exposure generally does not trouble most people. However, it is vital to ensure protection for babies, children, and individuals with sensitive skin. Given the potency of the midday Sun's UV radiation, one should avoid prolonged exposure. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Boulder, CO
- Average high temperature in December: 35.2°F
The warmest month (with the highest average high temperature) is July (80.4°F).
The month with the lowest average high temperature is December (35.2°F).
- Average low temperature in December: 18.1°F
The month with the highest average low temperature is July (55.2°F).
The coldest month (with the lowest average low temperature) is February (18°F).
Average pressure in December
Boulder, CO
- Average pressure in December: 30.13"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The months with the lowest atmospheric pressure are April, May and June (29.92"Hg).
Average wind speed in December
Boulder, CO
- Average wind speed in December: 6.8mph
The windiest month (with the highest average wind speed) is January (7.3mph).
The calmest months (with the lowest average wind speed) are May, July, August and September (5.7mph).
Average humidity in December
Boulder, CO
- Average humidity in December: 65%
The month with the highest relative humidity is February (70%).
The months with the lowest relative humidity are June, August and September (45%).
Average rainfall in December
Boulder, CO
- Average rainfall in December: 0.51"
The wettest month (with the highest rainfall) is May (2.48").
The driest month (with the least rainfall) is January (0.39").
Average rainfall days in December
Boulder, CO
- Average rainfall days in December: 3.9 days
The month with the highest number of rainy days is July (17.8 days).
The month with the least rainy days is November (3.3 days).
Average snowfall in December
Boulder, CO
- Average snowfall in December: 3.94"
The month with the highest snowfall is April (7.76").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Boulder, CO
- Average snowfall days in December: 7.2 days
The month with the highest number of snowfall days is February (10.3 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in December /
Average sunshine in December
Boulder, CO
- Average daylight in December: 9h and 24min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in December: 6h and 48min
The months with the most sunshine are June and July (Average sunshine: 11h and 42min).
The month with the least sunshine is February (Average sunshine: 6h and 36min).
Average sunshine days in December
Boulder, CO
- Average sunshine days in December: 21.9 days
The month with the most sunshine days is January (22.2 days).
The month with the least sunshine days is July (9.9 days).
Average UV index in December
Boulder, CO
- Average UV index in December: 2
The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in December
Boulder, CO
- Average cloud cover in December: 24
The months with the most cloud cover are April and May (Cloud cover 28).
The month with the least cloud cover is September (Cloud cover 16).
Average visibility in December
Boulder, CO
- 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).
