December weather forecast and climate
Mill Valley, CA

Weather in December

The first month of the winter, December, is still a mild month in Mill Valley, California, with average temperature varying between 55.4°F (13°C) and 45.3°F (7.4°C).

Temperature

December is the coldest month, with an average high-temperature of 55.4°F (13°C) and an average low-temperature of 45.3°F (7.4°C).

Humidity

The average relative humidity is 73%.

Rainfall

In Mill Valley, during December, the rain falls for 7.2 days and regularly aggregates up to 0.67" (17mm) of precipitation. In Mill Valley, during the entire year, the rain falls for 48 days and collects up to 3.94" (100mm) of precipitation.

Daylight

The month with the shortest days in Mill Valley is December, with an average of 9.6h of daylight.

Sunshine

December has the least sunshine of the year in Mill Valley, California, with an average of 5.5h of sunshine.

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 medium vulnerability from the exposure to the Sun's UV rays for average individuals.
Note: The daily maximum UV index of 3 in December interpret into the following advice:
Take precautions - Protection against sunburn is recommended. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.
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FAQ

What is the coldest month in Mill Valley?

December is the coldest month in Mill Valley, with an average high-temperature of 55.4°F (13°C) and an average low-temperature of 45.3°F (7.4°C).

What is the temperature in December in Mill Valley?

In Mill Valley, California, in December, the average high-temperature is 55.4°F (13°C), and the average low-temperature is 45.3°F (7.4°C).

What is the average humidity in December in Mill Valley?

In Mill Valley, California, the average relative humidity in December is 73%.

How many days does it rain in December in Mill Valley?

In Mill Valley, in December, it is raining for 7.2 days, with typically 0.67" (17mm) of accumulated precipitation.

What is the month with the shortest days in Mill Valley?

The month with the shortest days is December, with an average of 9.6h of daylight.

What is the average length of the day in December in Mill Valley?

In December, the average length of the day in Mill Valley is 9.6h.

What is the month with the least sunshine in Mill Valley?

The month with the least sunshine in Mill Valley, California, is December, with an average of 5.5h of sunshine.

How many hours of sunshine does Mill Valley have in December?

In December, the average sunshine in Mill Valley, California, is 5.5h.

When is the lowest UV index in Mill Valley?

January, February, November and December, with an average maximum UV index of 3, are months with the lowest UV index in Mill Valley, California.

How high is the UV index in December in Mill Valley?

The average daily maximum UV index in December in Mill Valley, California, is 3. A UV Index of 3 to 5 symbolizes a medium health risk from the exposure to the Sun's UV rays.

Average temperature in December
Mill Valley, CA

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).

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Average pressure in December
Mill Valley, CA

Average pressure in December - Mill Valley, CA
  • Average pressure in December: 30.1"

The month with the highest atmospheric pressure is January (30.13").
Months with the lowest atmospheric pressure are June, August and September (29.92").

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Average wind speed in December
Mill Valley, CA

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).

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Average humidity in December
Mill Valley, CA

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%).

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Average rainfall in December
Mill Valley, CA

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").

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Average rainfall days in December
Mill Valley, CA

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).
Months with the least rainy days are June and August (1.2 days).

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Average daylight in December /
Average sunshine in December
Mill Valley, CA

Average daylight in December / Average sunshine in December - Mill Valley, CA
  • Average daylight in December: 9.6h

The month with the longest days is June (Average daylight: 14.8h).
The month with the shortest days is December (Average daylight: 9.6h).

  • Average sunshine in December: 5.5h

The month with the most sunshine is July (Average sunshine: 11.2h).
The month with the least sunshine is December (Average sunshine: 5.5h).

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Average sunshine days in December
Mill Valley, CA

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).

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Average UV index in December
Mill Valley, CA

Average UV index in December - Mill Valley, CA
  • Average UV index in December: 3

Months with the highest UV index are April, June, July, August and September (UV index 5).
Months with the lowest UV index are January, February, November and December (UV index 3).

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Average cloud cover in December
Mill Valley, CA

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).

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Average visibility in December
Mill Valley, CA

Average visibility in December - Mill Valley, CA
  • Average visibility in December: 6mi

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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