December weather forecastSanta Rosa, CA
December
Weather in December
Closing out the year, December in Santa Rosa epitomizes the winter season in the city. Though temperatures and daylight hours fall noticeably from November levels, the winter here is relatively mild and temperate. Correspondingly, the increase in rainfall from 1.02" (26mm) to 2.24" (57mm) in December highlights the winter imprint. Moreover, the increase in relative humidity and cloud percentage corroborates the winter pattern. The relatively constant wind speed, visibility, and pressure emphasize the overall stability of Santa Rosa's winter climate.Temperature
December proves to be the coldest month in Santa Rosa, recording an average maximum temperature of 55.6°F (13.1°C) and a minimum temperature of 41.9°F (5.5°C).Humidity
In Santa Rosa, the average relative humidity in December is 75%.Rainfall
In Santa Rosa, California, during December, the rain falls for 10.5 days and regularly aggregates up to 2.24" (57mm) of precipitation. In Santa Rosa, during the entire year, the rain falls for 72.8 days and collects up to 12.01" (305mm) of precipitation.Daylight
The month with the shortest days is December, with an average of 9h and 30min of daylight.On the first day of the month, sunrise is at 7:09 am and sunset at 4:50 pm. On the last day of December, sunrise is at 7:28 am and sunset at 5:00 pm PST.
Sunshine
The month with the least sunshine in Santa Rosa, California, is December, with an average of 5.7h of sunshine.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 3. A UV Index value of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for average individuals.Note: In December, an average UV index of 3 transforms into the following instructions:
Be vigilant - A duty to shield skin and eyes from injury exists. Exposing oneself to the midday Sun can be harmful due to the strong UV radiation; limit your time outside. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Santa Rosa, CA
- Average high temperature in December: 55.6°F
The warmest month (with the highest average high temperature) is August (79.7°F).
The month with the lowest average high temperature is December (55.6°F).
- Average low temperature in December: 41.9°F
The months with the highest average low temperature are August and September (54.7°F).
The coldest month (with the lowest average low temperature) is December (41.9°F).
Average pressure in December
Santa Rosa, CA
- Average pressure in December: 30.1"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
Santa Rosa, CA
- Average wind speed in December: 5.2mph
The windiest month (with the highest average wind speed) is May (7.1mph).
The calmest month (with the lowest average wind speed) is November (4.9mph).
Average humidity in December
Santa Rosa, CA
- Average humidity in December: 75%
The month with the highest relative humidity is March (77%).
The month with the lowest relative humidity is September (63%).
Average rainfall in December
Santa Rosa, CA
- Average rainfall in December: 2.24"
The wettest month (with the highest rainfall) is February (2.64").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in December
Santa Rosa, CA
- Average rainfall days in December: 10.5 days
The month with the highest number of rainy days is March (12.6 days).
The month with the least rainy days is August (0.8 days).
Average daylight in December /
Average sunshine in December
Santa Rosa, CA
- Average daylight in December: 9h and 30min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in December: 5h and 42min
The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).
Average sunshine days in December
Santa Rosa, CA
- Average sunshine days in December: 19.5 days
The month with the most sunshine days is July (27.2 days).
The month with the least sunshine days is March (17.1 days).
Average UV index in December
Santa Rosa, 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 January, February, November and December (UV index 3).
Average cloud cover in December
Santa Rosa, CA
- Average cloud cover in December: 37
The month with the most cloud cover is March (Cloud cover 39).
The month with the least cloud cover is July (Cloud cover 9).
Average visibility in December
Santa Rosa, 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).
