December weather forecastRiverdale, CA
December
Weather in December
December, the first month of the winter in Riverdale, is still a refreshing month, with an average temperature ranging between min 43°F (6.1°C) and max 57.2°F (14°C).Temperature
The coldest period tends to be December, when average temperatures fluctuate between a high of 57.2°F (14°C) and a low of 43°F (6.1°C).Humidity
The months with the highest humidity are January and December, with an average relative humidity of 66%.Rainfall
In Riverdale, in December, it is raining for 8.2 days, with typically 1.42" (36mm) of accumulated precipitation. In Riverdale, during the entire year, the rain falls for 58.2 days and collects up to 9.29" (236mm) of precipitation.Daylight
The month with the shortest days is December, with an average of 9h and 42min of daylight.On the first day of the month, sunrise is at 6:53 am and sunset at 4:44 pm. On the last day of December, sunrise is at 7:11 am and sunset at 4:54 pm PST.
Sunshine
The month with the least sunshine is December, with an average of 6.4h of sunshine.UV index
The months with the lowest UV index are January, November and December, with an average maximum UV index of 3. A UV Index reading of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV rays for the average person.Note: The daily high UV index of 3 during December translates into the following recommendations:
Preventative actions are necessary - Recommendations to ward off sunburn are given. For skin protection, it's recommended to minimize Sun exposure during its peak hours around midday. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Riverdale, CA
- Average high temperature in December: 57.2°F
The warmest month (with the highest average high temperature) is July (102.2°F).
The month with the lowest average high temperature is December (57.2°F).
- Average low temperature in December: 43°F
The month with the highest average low temperature is July (66.9°F).
The coldest month (with the lowest average low temperature) is December (43°F).
Average pressure in December
Riverdale, 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 (29.89"Hg).
Average wind speed in December
Riverdale, CA
- Average wind speed in December: 4.9mph
The windiest month (with the highest average wind speed) is June (7.1mph).
The calmest months (with the lowest average wind speed) are January and November (4.8mph).
Average humidity in December
Riverdale, CA
- Average humidity in December: 66%
The months with the highest relative humidity are January and December (66%).
The month with the lowest relative humidity is July (30%).
Average rainfall in December
Riverdale, CA
- Average rainfall in December: 1.42"
The wettest months (with the highest rainfall) are January, February and March (1.54").
The driest month (with the least rainfall) is August (0.08").
Average rainfall days in December
Riverdale, CA
- Average rainfall days in December: 8.2 days
The month with the highest number of rainy days is March (9.6 days).
The month with the least rainy days is August (0.8 days).
Average daylight in December /
Average sunshine in December
Riverdale, 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: 6h and 24min
The months with the most sunshine are June and July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 24min).
Average sunshine days in December
Riverdale, CA
- Average sunshine days in December: 21.8 days
The month with the most sunshine days is August (29.3 days).
The month with the least sunshine days is February (19.4 days).
Average UV index in December
Riverdale, CA
- Average UV index in December: 3
The months with the highest UV index are June, July and August (UV index 7).
The months with the lowest UV index are January, November and December (UV index 3).
Average cloud cover in December
Riverdale, CA
- Average cloud cover in December: 28
The months with the most cloud cover are March and December (Cloud cover 28).
The month with the least cloud cover is August (Cloud cover 4).
Average visibility in December
Riverdale, 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).
