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
The coldest temperatures occur during December, when averages reach a peak of 56.3°F (13.5°C) and a low of 43.7°F (6.5°C).Humidity
In Union City, the average relative humidity in December is 70%.Rainfall
In Union City, during December, the rain falls for 6.3 days and regularly aggregates up to 0.35" (9mm) of precipitation. Throughout the year, there are 38 rainfall days, and 2.13" (54mm) 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 the month, sunrise is at 7:05 am and sunset at 4:50 pm. On the last day of December, in Union City, sunrise is at 7:22 am and sunset at 5:00 pm PST.
Sunshine
The month with the least sunshine is December, with an average of 6h of sunshine.UV index
The months with the lowest UV index in Union City are January, February, November and December, with an average maximum UV index of 3. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for the ordinary person.Note: An average UV index of 3 in December transforms into this advice:
Guard yourself - Avoiding sunburn is suggested. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation.
Frequently asked questions
What month is the coldest in Union City?
What is the average December temperature in Union City?
What is the average humidity in December in Union City?
How many days does it rain in December in Union City?
What is the month with the shortest days in Union City?
What is the average length of the day in December in Union City?
When are sunrise and sunset in December in Union City?
What is the month with the least sunshine in Union City?
How many hours of sunshine does Union City have in December?
What is the month with the lowest UV index in Union City?
What is the UV index intensity in December in Union City?
Average temperature in December
Union City, CA
- Average high temperature in December: 56.3°F
The warmest months (with the highest average high temperature) are July and August (80.1°F).
The month with the lowest average high temperature is December (56.3°F).
- Average low temperature in December: 43.7°F
The months with the highest average low temperature are August and September (56.7°F).
The coldest month (with the lowest average low temperature) is December (43.7°F).
Average pressure in December
Union City, 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, August and September (29.92"Hg).
Average wind speed in December
Union City, CA
- Average wind speed in December: 5.3mph
The windiest month (with the highest average wind speed) is May (6.4mph).
The calmest months (with the lowest average wind speed) are October and November (4.7mph).
Average humidity in December
Union City, CA
- Average humidity in December: 70%
The month with the highest relative humidity is March (73%).
The months with the lowest relative humidity are September and October (62%).
Average rainfall in December
Union City, CA
- Average rainfall in December: 0.35"
The wettest month (with the highest rainfall) is February (0.47").
The driest months (with the least rainfall) are June, July and August (0").
Average rainfall days in December
Union City, CA
- Average rainfall days in December: 6.3 days
The month with the highest number of rainy days is March (7.3 days).
The month with the least rainy days is July (0.3 days).
Average daylight in December /
Average sunshine in December
Union City, 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: 6h and 0min
The month with the most sunshine is July (Average sunshine: 12h and 12min).
The month with the least sunshine is December (Average sunshine: 6h and 0min).
Average sunshine days in December
Union City, CA
- Average sunshine days in December: 24 days
The months with the most sunshine days are July and August (30.4 days).
The month with the least sunshine days is February (22.2 days).
Average UV index in December
Union City, CA
- Average UV index in December: 3
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in December
Union City, CA
- Average cloud cover in December: 33
The month with the most cloud cover is March (Cloud cover 34).
The month with the least cloud cover is July (Cloud cover 6).
Average visibility in December
Union City, 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).
Union City, California, USA
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