December weather forecastJohnstown, CA
December
Weather in December
December, the first month of the winter in Johnstown, is also an enjoyable month, with an average temperature fluctuating between 63.7°F (17.6°C) and 46.6°F (8.1°C).Temperature
With average high and low temperatures of 63.7°F (17.6°C) and 46.6°F (8.1°C) respectively, December is Johnstown's coldest month.Humidity
In Johnstown, the average relative humidity in December is 58%.Rainfall
In December, the rain falls for 5.1 days. Throughout December, 0.71" (18mm) of precipitation is accumulated. In Johnstown, during the entire year, the rain falls for 49.6 days and collects up to 5.16" (131mm) of precipitation.Daylight
With an average of 10h and 0min of daylight, December has the shortest days of the year.On the first day of December, sunrise is at 6:32 am and sunset at 4:41 pm. On the last day of the month, sunrise is at 6:50 am and sunset at 4:51 pm PST.
Sunshine
The month with the least sunshine is December, with an average of 6.7h of sunshine.UV index
With an average maximum UV index of 3, December is the month with the lowest UV index. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for ordinary individuals.Note: The maximum UV index of 3 during December translates into these guidelines:
Undertake precautions - Guarding against sun damage is counselled. Being exposed to the midday Sun can have harmful effects due to strong UV radiation; always take precautions. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Johnstown, CA
- Average high temperature in December: 63.7°F
The warmest month (with the highest average high temperature) is August (85.5°F).
The month with the lowest average high temperature is December (63.7°F).
- Average low temperature in December: 46.6°F
The month with the highest average low temperature is August (64.9°F).
The coldest month (with the lowest average low temperature) is February (46°F).
Average pressure in December
Johnstown, CA
- Average pressure in December: 30.06"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).
Average wind speed in December
Johnstown, CA
- Average wind speed in December: 4.8mph
The windiest months (with the highest average wind speed) are April and May (5.3mph).
The calmest months (with the lowest average wind speed) are August, September and October (4.2mph).
Average humidity in December
Johnstown, CA
- Average humidity in December: 58%
The month with the highest relative humidity is May (65%).
The month with the lowest relative humidity is November (52%).
Average rainfall in December
Johnstown, CA
- Average rainfall in December: 0.71"
The wettest month (with the highest rainfall) is February (1.06").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in December
Johnstown, CA
- Average rainfall days in December: 5.1 days
The month with the highest number of rainy days is March (6.8 days).
The month with the least rainy days is June (1.4 days).
Average daylight in December /
Average sunshine in December
Johnstown, CA
- Average daylight in December: 10h and 0min
The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).
- Average sunshine in December: 6h and 42min
The months with the most sunshine are June and July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).
Average sunshine days in December
Johnstown, CA
- Average sunshine days in December: 25.2 days
The month with the most sunshine days is June (28 days).
The month with the least sunshine days is July (20.7 days).
Average UV index in December
Johnstown, CA
- Average UV index in December: 3
The months with the highest UV index are June, July, August and September (UV index 6).
The month with the lowest UV index is December (UV index 3).
Average cloud cover in December
Johnstown, CA
- Average cloud cover in December: 23
The months with the most cloud cover are March and December (Cloud cover 23).
The month with the least cloud cover is August (Cloud cover 6).
Average visibility in December
Johnstown, CA
- 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).
