December weather forecastJohnstown, CO
December
Weather in December
December marks the inception of winter, with Johnstown, Colorado, transforming into a winter wonderland. Temperatures plunge to a frigid 20.7°F (-6.3°C), with a corresponding increase in snowfall to 2.76" (70mm). Limited daylight hours, accompanied by a higher percentage of cloud cover, induce a cozy, festive atmosphere. Despite the chill, the snow-laden landscapes of Johnstown offer a unique charm, enchanting residents and visitors alike.Temperature
Johnstown's coldest month, December, registers temperatures that range from a high of 39.4°F (4.1°C) to a low of 20.7°F (-6.3°C).Humidity
The months with the highest humidity in Johnstown are January, February and December, with an average relative humidity of 63%.Rainfall
The months with the least rainfall in Johnstown are January and December Rain falls for 5.2 days and accumulates 0.39" (10mm) of rain.Snowfall
Months with snowfall in Johnstown are January through May, October through December. In Johnstown, Colorado, during December, snow falls for 7 days and regularly aggregates up to 2.76" (70mm) of snow. In Johnstown, Colorado, during the entire year, snow falls for 41 days and aggregates up to 25.51" (648mm) of snow.Daylight
December has the shortest days of the year in Johnstown, with an average of 9h and 24min of daylight.On the first day of the month, sunrise is at 7:03 am and sunset at 4:33 pm. On the last day of December, in Johnstown, sunrise is at 7:22 am and sunset at 4:43 pm MST.
Sunshine
In December, the average sunshine is 6.9h.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Johnstown, Colorado. A UV Index estimate of 2, and below, represents a minimal health hazard from exposure to the Sun's UV radiation for the ordinary person.Note: The maximum daily UV index of 2 during December translates into the following directions:
Long-term sun exposure is typically not a concern for most. However, those with sensitive skin, infants, and children must always have protection. During midday, the Sun's radiation is strongest, and it's advisable to reduce direct exposure. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes. Be careful! The Sun's UV radiation can nearly be doubled by the reflective quality of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Johnstown, CO
- Average high temperature in December: 39.4°F
The warmest month (with the highest average high temperature) is July (88.7°F).
The month with the lowest average high temperature is December (39.4°F).
- Average low temperature in December: 20.7°F
The month with the highest average low temperature is July (61.3°F).
The coldest month (with the lowest average low temperature) is December (20.7°F).
Average pressure in December
Johnstown, CO
- Average pressure in December: 30.12"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in December
Johnstown, CO
- Average wind speed in December: 5.5mph
The windiest month (with the highest average wind speed) is April (7.3mph).
The calmest month (with the lowest average wind speed) is December (5.5mph).
Average humidity in December
Johnstown, CO
- Average humidity in December: 63%
The months with the highest relative humidity are January, February and December (63%).
The months with the lowest relative humidity are August and September (42%).
Average rainfall in December
Johnstown, CO
- Average rainfall in December: 0.39"
The wettest month (with the highest rainfall) is May (2.13").
The driest months (with the least rainfall) are January and December (0.39").
Average rainfall days in December
Johnstown, CO
- Average rainfall days in December: 5.2 days
The month with the highest number of rainy days is May (14.3 days).
The month with the least rainy days is November (3.7 days).
Average snowfall in December
Johnstown, CO
- Average snowfall in December: 2.76"
The month with the highest snowfall is February (4.53").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Johnstown, CO
- Average snowfall days in December: 7 days
The month with the highest number of snowfall days is February (9.6 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in December /
Average sunshine in December
Johnstown, 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 54min
The month with the most sunshine is June (Average sunshine: 11h and 54min).
The month with the least sunshine is February (Average sunshine: 6h and 42min).
Average sunshine days in December
Johnstown, CO
- Average sunshine days in December: 22.2 days
The month with the most sunshine days is January (22.4 days).
The month with the least sunshine days is July (11.4 days).
Average UV index in December
Johnstown, CO
- 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, November and December (UV index 2).
Average cloud cover in December
Johnstown, CO
- Average cloud cover in December: 24
The month with the most cloud cover is April (Cloud cover 27).
The months with the least cloud cover are June and September (Cloud cover 16).
Average visibility in December
Johnstown, 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).
