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
December, with an average high of 56.8°F (13.8°C) and a low of 44.2°F (6.8°C), signifies the coldest month of the year.Humidity
In Sunnyvale, the average relative humidity in December is 71%.Rainfall
In Sunnyvale, in December, it is raining for 7.5 days, with typically 0.71" (18mm) of accumulated precipitation. Throughout the year, there are 50 rainfall days, and 3.9" (99mm) of precipitation is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 36min of daylight.On the first day of December, sunrise is at 7:04 am and sunset at 4:50 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 5:00 pm PST.
Sunshine
With an average of 5.9h of sunshine, December has the least sunshine of the year in Sunnyvale.UV index
The months with the lowest UV index are February, November and December, with an average maximum UV index of 3. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for average individuals.Note: The maximum daily UV index of 3 during December translates into the following directions:
Make use of precautions - Suggestions to resist sunburn are communicated. Around midday, solar radiation is most harmful; hence, exposure should be limited. Shield yourself from the harmful effects of UV radiation with sun-protective attire, a hat, and quality sunglasses.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
What month is the coldest?
What is the temperature in December?
What is the average humidity in December in Sunnyvale?
How much does it rain 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?
How long on average sun shines in December?
What is the month with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Sunnyvale, CA
- Average high temperature in December: 56.8°F
The warmest month (with the highest average high temperature) is July (79.9°F).
The month with the lowest average high temperature is December (56.8°F).
- Average low temperature in December: 44.2°F
The month with the highest average low temperature is August (56.8°F).
The coldest months (with the lowest average low temperature) are February and December (44.2°F).
Average pressure in December
Sunnyvale, CA
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The months with the lowest atmospheric pressure are June and September (29.92"Hg).
Average wind speed in December
Sunnyvale, CA
- Average wind speed in December: 5.3mph
The windiest month (with the highest average wind speed) is April (6.2mph).
The calmest month (with the lowest average wind speed) is September (4.6mph).
Average humidity in December
Sunnyvale, CA
- Average humidity in December: 71%
The month with the highest relative humidity is March (73%).
The months with the lowest relative humidity are September and October (63%).
Average rainfall in December
Sunnyvale, CA
- Average rainfall in December: 0.71"
The wettest months (with the highest rainfall) are February and March (0.75").
The driest month (with the least rainfall) is July (0").
Average rainfall days in December
Sunnyvale, CA
- Average rainfall days in December: 7.5 days
The month with the highest number of rainy days is March (9.6 days).
The month with the least rainy days is August (0.4 days).
Average daylight in December /
Average sunshine in December
Sunnyvale, CA
- Average daylight in December: 9h and 4min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in December: 5h and 5min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).
Average sunshine days in December
Sunnyvale, CA
- Average sunshine days in December: 22.4 days
The month with the most sunshine days is August (30.1 days).
The month with the least sunshine days is March (19.9 days).
Average UV index in December
Sunnyvale, CA
- Average UV index in December: 3
The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are February, November and December (UV index 3).
Average cloud cover in December
Sunnyvale, CA
- Average cloud cover in December: 33
The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 7).
Average visibility in December
Sunnyvale, 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).
Sunnyvale, California, USA
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