December weather forecastSwansea, CA
December
Weather in December
The first month of the winter, December, is still a chilly month in Swansea, California, with temperature in the range of an average low of 31.5°F (-0.3°C) and an average high of 46.9°F (8.3°C).Temperature
In Swansea, the month of December is known for its lowest average temperatures, reaching a high of 46.9°F (8.3°C) and a low of 31.5°F (-0.3°C).Humidity
The most humid month is December, with an average relative humidity of 47%.Rainfall
December is the month with the most rainfall. Rain falls for 5.1 days and accumulates 0.67" (17mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. The month with the most snowfall is December, when snow falls for 1.2 days and typically aggregates up to 1.18" (30mm) of snow.Daylight
December has the shortest days of the year, with an average of 9h and 42min of daylight.On the first day of December, sunrise is at 6:45 am and sunset at 4:36 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 4:46 pm PST.
Sunshine
January, February and December, with an average of 7.3h of sunshine, are months with the least sunshine.UV index
November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index reading of 2, and below, represents a low health risk from exposure to the Sun's UV rays for ordinary individuals.Note: An average maximum UV index of 2 in December leads to these recommendations:
Long-term sun exposure is typically not a concern for most. However, those with sensitive skin, infants, and children must always have protection. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays. Pay attention! The reflection of snow can enhance the Sun's UV radiation almost double.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Swansea, CA
- Average high temperature in December: 46.9°F
The warmest month (with the highest average high temperature) is July (86°F).
The month with the lowest average high temperature is December (46.9°F).
- Average low temperature in December: 31.5°F
The month with the highest average low temperature is July (69.1°F).
The coldest month (with the lowest average low temperature) is December (31.5°F).
Average pressure in December
Swansea, 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 (29.83"Hg).
Average wind speed in December
Swansea, CA
- Average wind speed in December: 6.2mph
The windiest months (with the highest average wind speed) are April, May and June (7.6mph).
The calmest month (with the lowest average wind speed) is November (5.8mph).
Average humidity in December
Swansea, CA
- Average humidity in December: 47%
The month with the highest relative humidity is December (47%).
The month with the lowest relative humidity is August (19%).
Average rainfall in December
Swansea, CA
- Average rainfall in December: 0.67"
The wettest month (with the highest rainfall) is December (0.67").
The driest months (with the least rainfall) are June and September (0.16").
Average rainfall days in December
Swansea, CA
- Average rainfall days in December: 5.1 days
The month with the highest number of rainy days is March (5.7 days).
The month with the least rainy days is September (2.3 days).
Average snowfall in December
Swansea, CA
- Average snowfall in December: 1.18"
The month with the highest snowfall is December (1.18").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Swansea, CA
- Average snowfall days in December: 1.2 days
The month with the highest number of snowfall days is December (1.2 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
Swansea, CA
- Average daylight in December: 9h and 42min
The month with the longest days is June (Average daylight: 14h and 36min).
The month with the shortest days is December (Average daylight: 9h and 42min).
- Average sunshine in December: 7h and 18min
The month with the most sunshine is June (Average sunshine: 12h and 12min).
The months with the least sunshine are January, February and December (Average sunshine: 7h and 18min).
Average sunshine days in December
Swansea, CA
- Average sunshine days in December: 25.3 days
The month with the most sunshine days is October (27.7 days).
The month with the least sunshine days is July (20 days).
Average UV index in December
Swansea, 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 November and December (UV index 2).
Average cloud cover in December
Swansea, CA
- Average cloud cover in December: 15
The month with the most cloud cover is January (Cloud cover 16).
The months with the least cloud cover are August and September (Cloud cover 5).
Average visibility in December
Swansea, 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).
