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 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
With average high temperatures of 54.9°F (12.7°C) and lows of 42.3°F (5.7°C), December is the coldest month.Humidity
The average relative humidity in December is 72%.Rainfall
In Napa Junction, California, in December, it is raining for 9.9 days, with typically 2.13" (54mm) of accumulated precipitation. In Napa Junction, during the entire year, the rain falls for 68.2 days and collects up to 11.93" (303mm) of precipitation.Daylight
With an average of 9h and 36min of daylight, December has the shortest days of the year in Napa Junction, California.On the first day of December in Napa Junction, sunrise is at 7:07 am and sunset at 4:49 pm. On the last day of the month, sunrise is at 7:25 am and sunset at 4:59 pm PST.
Sunshine
December has the least sunshine of the year in Napa Junction, with an average of 5.7h of sunshine.UV index
The months with the lowest UV index in Napa Junction are January, February, November and December, with an average maximum UV index of 3. A UV Index estimate of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for the ordinary person.Note: An average maximum UV index of 3 in December leads to these recommendations:
Make use of precautions - It is urged to ward off sun damage. When the Sun is at its strongest around midday, find shade and limit exposure. A wide-brimmed hat provides unparalleled sun protection for sensitive areas like the eyes, ears, and neck.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What part of the year is the coldest in Napa Junction?
What are the temperatures in Napa Junction in December?
What is the average humidity in December in Napa Junction?
How many days does it rain in December in Napa Junction?
What is the month with the shortest days in Napa Junction?
How many hours of daylight does Napa Junction have in December?
When are sunrise and sunset in December in Napa Junction?
What is the month with the least sunshine in Napa Junction?
How many hours of sunshine does Napa Junction have in December?
When is the lowest UV index in Napa Junction?
What is the UV index reading in December in Napa Junction?
Average temperature in December
Napa Junction, CA
- Average high temperature in December: 54.9°F
The warmest month (with the highest average high temperature) is July (82.6°F).
The month with the lowest average high temperature is December (54.9°F).
- Average low temperature in December: 42.3°F
The month with the highest average low temperature is August (56.5°F).
The coldest months (with the lowest average low temperature) are January and December (42.3°F).
Average pressure in December
Napa Junction, CA
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in December
Napa Junction, CA
- Average wind speed in December: 4.9mph
The windiest month (with the highest average wind speed) is May (6.6mph).
The calmest month (with the lowest average wind speed) is November (4.5mph).
Average humidity in December
Napa Junction, CA
- Average humidity in December: 72%
The month with the highest relative humidity is March (75%).
The month with the lowest relative humidity is September (58%).
Average rainfall in December
Napa Junction, CA
- Average rainfall in December: 2.13"
The wettest month (with the highest rainfall) is February (2.32").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in December
Napa Junction, CA
- Average rainfall days in December: 9.9 days
The month with the highest number of rainy days is March (11.9 days).
The month with the least rainy days is August (0.9 days).
Average daylight in December /
Average sunshine in December
Napa Junction, CA
- Average daylight in December: 9h and 4min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in December: 5h and 4min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).
Average sunshine days in December
Napa Junction, CA
- Average sunshine days in December: 20.1 days
The months with the most sunshine days are July and August (29.1 days).
The month with the least sunshine days is March (18.3 days).
Average UV index in December
Napa Junction, CA
- Average UV index in December: 3
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 3).
Average cloud cover in December
Napa Junction, CA
- Average cloud cover in December: 36
The month with the most cloud cover is March (Cloud cover 37).
The month with the least cloud cover is July (Cloud cover 7).
Average visibility in December
Napa Junction, 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).
Napa Junction, California, USA
Weather forecast for your location
2. Allow the app to use your location