December weather forecast
Gilroy, CA

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A colorful sunset sky over the hilly region of Gilroy in California
A colorful sunset sky over the hilly region of Gilroy in California

Weather in December

The first month of the winter, December, is still a refreshing month in Gilroy, California, with an average temperature varying between 57.6°F (14.2°C) and 41.2°F (5.1°C).

Temperature

With its high average temperature of 57.6°F (14.2°C) and a low of 41.2°F (5.1°C), December is regarded as the coldest month.

Humidity

In December, the average relative humidity is 71%.

Rainfall

The month with the most rainfall is December, when the rain falls for 6.6 days and typically aggregates up to 0.83" (21mm) of precipitation.

Daylight

With an average of 9h and 42min of daylight, December has the shortest days of the year.
On the first day of December, sunrise is at 7:01 am and sunset at 4:49 pm. On the last day of the month, sunrise is at 7:19 am and sunset at 4:59 pm PST.

Sunshine

With an average of 6h of sunshine, December has the least sunshine of the year.

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 reading of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV rays for the ordinary person.
Note: A maximum high UV index of 3 in December translates into the following recommendations:
Take precautions - Protection against skin and eye damage is obliged. Minimize direct exposure to the Sun during midday when its radiation is at its peak. Shield yourself from the harmful effects of UV radiation with sun-protective attire, a hat, and quality sunglasses.

Frequently asked questions

What part of the year is the coldest?

December stands out as Gilroy's coldest month, with temperatures ranging between an average high of 57.6°F (14.2°C) and a low of 41.2°F (5.1°C).

What is the temperature in December?

The average high-temperature, in December, in Gilroy, is 57.6°F (14.2°C), while the average low-temperature is 41.2°F (5.1°C). In September, the average heat index (a.k.a. 'feels like', 'real feel'), which combines air temperature and relative humidity, is calculated to be 86°F (30°C).

What is the average humidity in December?

The average relative humidity in December is 71%.

What is the rainiest month?

December is the month with the most rainfall. Rain falls for 6.6 days and accumulates 0.83" (21mm) of precipitation.

How many days does it rain in December?

In December, the rain falls for 6.6 days. Throughout December, 0.83" (21mm) of precipitation is accumulated.

What is the month with the shortest days in Gilroy?

The month with the shortest days is December, with an average of 9h and 42min of daylight.

How many hours of daylight does Gilroy have in December?

The average day length in December is 9h and 40min.

When is the sunrise / sunset in December?

In December, on the first day of the month, sunrise is at 7:01 am and sunset at 4:49 pm. On the last day of the month, sunrise is at 7:19 am and sunset at 4:59 pm PST.

What is the month with the least sunshine?

The month with the least sunshine is December, with an average of 6h of sunshine.

How many hours of sunshine does Gilroy have in December?

The average sunshine duration in December is 6h.

When is the lowest UV index?

The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 3.

What is the UV index intensity in December?

The average daily maximum UV index in December is 3. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Gilroy, CA

Average temperature in December - Gilroy, CA
  • Average high temperature in December: 57.6°F

The warmest month (with the highest average high temperature) is August (85.1°F).
The month with the lowest average high temperature is December (57.6°F).

  • Average low temperature in December: 41.2°F

The months with the highest average low temperature are August and September (54.1°F).
The coldest months (with the lowest average low temperature) are February and March (40.6°F).

Average pressure in December
Gilroy, CA

Average pressure in December - Gilroy, CA
  • Average pressure in December: 30.11"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).

Average wind speed in December
Gilroy, CA

Average wind speed in December - Gilroy, CA
  • Average wind speed in December: 4.1mph

The windiest month (with the highest average wind speed) is May (5.3mph).
The calmest month (with the lowest average wind speed) is November (3.9mph).

Average humidity in December
Gilroy, CA

Average humidity in December - Gilroy, CA
  • Average humidity in December: 71%

The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is September (57%).

Average rainfall in December
Gilroy, CA

Average rainfall in December - Gilroy, CA
  • Average rainfall in December: 0.83"

The wettest month (with the highest rainfall) is December (0.83").
The driest months (with the least rainfall) are June, July and August (0").

Average rainfall days in December
Gilroy, CA

Average rainfall days in December - Gilroy, CA
  • Average rainfall days in December: 6.6 days

The month with the highest number of rainy days is March (8.3 days).
The month with the least rainy days is August (0.6 days).

Average daylight in December /
Average sunshine in December
Gilroy, CA

Average daylight in December / Average sunshine in December - Gilroy, CA
  • Average daylight in December: 9h and 4min

The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 42min).

  • Average sunshine in December: 6h and 0min

The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 0min).

Average sunshine days in December
Gilroy, CA

Average sunshine days in December - Gilroy, CA
  • Average sunshine days in December: 23.2 days

The month with the most sunshine days is July (29.9 days).
The month with the least sunshine days is March (21.4 days).

Average UV index in December
Gilroy, CA

Average UV index in December - Gilroy, CA
  • Average UV index in December: 3

The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).

Average cloud cover in December
Gilroy, CA

Average cloud cover in December - Gilroy, CA
  • Average cloud cover in December: 34

The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 7).

Average visibility in December
Gilroy, CA

Average visibility in December - Gilroy, 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).

Gilroy, California, USA

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