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
The month of December sees the lowest average temperatures, reaching 47.8°F (8.8°C) at the peak and 33.6°F (0.9°C) at the low.Humidity
In O'Brien, the average relative humidity in December is 74%.Rainfall
In December, the rain falls for 12.7 days. Throughout December, 3.5" (89mm) of precipitation is accumulated. Throughout the year, there are 102.3 rainfall days, and 24.21" (615mm) of precipitation is accumulated.Snowfall
January through March, November and December are months with snowfall. In December, it is snowing for 1 days. Throughout December, 1.1" (28mm) of snow is accumulated. Throughout the year, in O'Brien, there are 4.6 snowfall days, and 4.45" (113mm) of snow is accumulated.Daylight
December has the shortest days of the year in O'Brien, with an average of 9h and 18min of daylight.On the first day of the month, sunrise is at 7:14 am and sunset at 4:42 pm. On the last day of December, sunrise is at 7:33 am and sunset at 4:51 pm PST.
Sunshine
December has the least sunshine of the year, with an average of 5.3h of sunshine.UV index
The months with the lowest UV index are February, November and December, with an average maximum UV index of 2. A UV Index value of 2, and less, symbolizes a low threat to health from unsafe exposure to UV radiation for average individuals.Note: In December, an average UV index of 2 transforms into the following instructions:
Apart from children, who require continuous protection, most can endure sun exposure for up to an hour without experiencing burns. It's recommended to limit sun exposure when its radiation is at its peak during midday. To cut down UV radiation exposure by about half, sport a wide-brim hat. Be aware! The reflective nature of snow can magnify the Sun's UV radiation almost twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What time of the year is the coldest in O'Brien?
What is the temperature in December?
What is the average humidity in December?
How many days does it rain in December?
How much does it snow in O'Brien in December?
What is the month with the shortest days?
What is the average length of the day in December?
When are sunrise and sunset in December?
What is the month with the least sunshine in O'Brien?
How long on average sun shines in December?
What is the month with the lowest UV index?
What is the UV index reading in December?
Average temperature in December
O'Brien, CA
- Average high temperature in December: 47.8°F
The warmest month (with the highest average high temperature) is July (91.6°F).
The month with the lowest average high temperature is December (47.8°F).
- Average low temperature in December: 33.6°F
The month with the highest average low temperature is July (59.4°F).
The coldest month (with the lowest average low temperature) is December (33.6°F).
Average pressure in December
O'Brien, CA
- Average pressure in December: 30.14"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.92"Hg).
Average wind speed in December
O'Brien, CA
- Average wind speed in December: 4.7mph
The windiest months (with the highest average wind speed) are March and October (5.3mph).
The calmest months (with the lowest average wind speed) are August and November (4.5mph).
Average humidity in December
O'Brien, CA
- Average humidity in December: 74%
The month with the highest relative humidity is March (77%).
The month with the lowest relative humidity is August (37%).
Average rainfall in December
O'Brien, CA
- Average rainfall in December: 3.5"
The wettest month (with the highest rainfall) is March (4.8").
The driest month (with the least rainfall) is July (0.12").
Average rainfall days in December
O'Brien, CA
- Average rainfall days in December: 12.7 days
The month with the highest number of rainy days is March (16.8 days).
The month with the least rainy days is August (1.7 days).
Average snowfall in December
O'Brien, CA
- Average snowfall in December: 1.1"
The month with the highest snowfall is November (1.3").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in December
O'Brien, CA
- Average snowfall days in December: 1 days
The month with the highest number of snowfall days is February (1.9 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
O'Brien, CA
- Average daylight in December: 9h and 2min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in December: 5h and 2min
The month with the most sunshine is July (Average sunshine: 12h and 12min).
The month with the least sunshine is December (Average sunshine: 5h and 18min).
Average sunshine days in December
O'Brien, CA
- Average sunshine days in December: 15.7 days
The month with the most sunshine days is August (27.1 days).
The month with the least sunshine days is March (11.8 days).
Average UV index in December
O'Brien, CA
- Average UV index in December: 2
The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are February, November and December (UV index 2).
Average cloud cover in December
O'Brien, CA
- Average cloud cover in December: 41
The month with the most cloud cover is March (Cloud cover 44).
The month with the least cloud cover is August (Cloud cover 5).
Average visibility in December
O'Brien, CA
- Average visibility in December: 5mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October and November (6mi).
The month with the lowest visibility is December (5mi).
O'Brien, California, USA
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