December weather forecastMill Valley, CA
December
Weather in December
The first month of the winter, December, is still a refreshing month in Mill Valley, California, with an average temperature ranging between max 55.4°F (13°C) and min 45.3°F (7.4°C).Temperature
The coldest period tends to be December, when average temperatures fluctuate between a high of 55.4°F (13°C) and a low of 45.3°F (7.4°C).Humidity
The average relative humidity in December is 73%.Rainfall
In Mill Valley, California, in December, it is raining for 7.2 days, with typically 0.67" (17mm) of accumulated precipitation. In Mill Valley, during the entire year, the rain falls for 48 days and collects up to 3.94" (100mm) of precipitation.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 7:07 am and sunset at 4:51 pm. On the last day of the month, sunrise is at 7:25 am and sunset at 5:01 pm PST.
Sunshine
With an average of 5.5h of sunshine, December has the least sunshine of the year.UV index
January, February, November and December, with an average maximum UV index of 3, are months with the lowest UV index. A UV Index reading of 3 to 5 represents a moderate health risk from unprotected exposure to Sun's UV rays for average individuals.Note: A maximum UV index of 3 in December translates into the following recommendations:
Put precautions into practice - Guidance to elude sunburn is provided. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. Opt for tightly woven and loose clothing to enhance protection from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Mill Valley, CA
- Average high temperature in December: 55.4°F
The warmest month (with the highest average high temperature) is September (72.3°F).
The month with the lowest average high temperature is December (55.4°F).
- Average low temperature in December: 45.3°F
The month with the highest average low temperature is September (56.1°F).
The coldest month (with the lowest average low temperature) is December (45.3°F).
Average pressure in December
Mill Valley, 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
Mill Valley, CA
- Average wind speed in December: 6.2mph
The windiest month (with the highest average wind speed) is May (7.8mph).
The calmest months (with the lowest average wind speed) are October and November (5.5mph).
Average humidity in December
Mill Valley, CA
- Average humidity in December: 73%
The month with the highest relative humidity is March (77%).
The month with the lowest relative humidity is October (68%).
Average rainfall in December
Mill Valley, CA
- Average rainfall in December: 0.67"
The wettest month (with the highest rainfall) is February (0.87").
The driest months (with the least rainfall) are June, July, August and September (0.04").
Average rainfall days in December
Mill Valley, CA
- Average rainfall days in December: 7.2 days
The month with the highest number of rainy days is March (8.8 days).
The months with the least rainy days are June and August (1.2 days).
Average daylight in December /
Average sunshine in December
Mill Valley, CA
- Average daylight in December: 9h and 36min
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 36min).
- Average sunshine in December: 5h and 30min
The month with the most sunshine is July (Average sunshine: 11h and 12min).
The month with the least sunshine is December (Average sunshine: 5h and 30min).
Average sunshine days in December
Mill Valley, CA
- Average sunshine days in December: 22.1 days
The month with the most sunshine days is June (26.4 days).
The month with the least sunshine days is March (20.7 days).
Average UV index in December
Mill Valley, CA
- Average UV index in December: 3
The months with the highest UV index are April, June, July, August and September (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in December
Mill Valley, CA
- Average cloud cover in December: 38
The month with the most cloud cover is March (Cloud cover 39).
The month with the least cloud cover is September (Cloud cover 19).
Average visibility in December
Mill Valley, 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).
