December weather forecast
Penryn, CA

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Weather in December

December, the first month of the winter in Penryn, is also a fresh month, with an average temperature ranging between min 39.2°F (4°C) and max 53.4°F (11.9°C).

Temperature

December tends to be the coldest month, with temperatures averaging a daily high of 53.4°F (11.9°C) and a low of 39.2°F (4°C).

Humidity

In December, the average relative humidity in Penryn, California, is 68%.

Rainfall

In December, the rain falls for 11.5 days. Throughout December, 4.69" (119mm) of precipitation is accumulated. Throughout the year, there are 84.8 rainfall days, and 28.86" (733mm) of precipitation is accumulated.

Snowfall

February, March and December are months with snowfall. December is the first month it typically snows. Throughout December, in the average 0.3 snowfall days, it receives 0.63" (16mm) of snow. In Penryn, California, during the entire year, snow falls for 1.2 days and aggregates up to 2.09" (53mm) of snow.

Daylight

With an average of 9h and 30min of daylight, December has the shortest days of the year.
On the first day of the month, sunrise is at 7:04 am and sunset at 4:43 pm. On the last day of December, sunrise is at 7:23 am and sunset at 4:53 pm PST.

Sunshine

The months with the least sunshine are January and December, with an average of 5.8h 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 reading of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for the ordinary person.
Note: A daily high UV index of 3 in December leads to these guidelines:
Ensure safety - Imperative it is to shield skin and eyes from damage. Limiting sun exposure during midday hours helps in reducing the harmful effects of UV radiation. On days when the sun blazes, arm yourself with sunglasses that block UVA and UVB radiation. Consider this! The reflection from snow can almost double the intensity of the Sun's UV radiation.
Updated: Aug 18, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the coldest month?

December is the month that records the lowest temperatures, with averages ranging from a high of 53.4°F (11.9°C) to a low of 39.2°F (4°C).

What is the usual temperature for Penryn in December?

During December, Penryn experiences an average high-temperature of 53.4°F (11.9°C) and a low-temperature of 39.2°F (4°C). The average heat index (a.k.a. 'feels like', 'felt air temperature'), which factors the actual air temperature with the relative humidity, in September is evaluated at 86°F (30°C).

What is the average humidity in December?

In Penryn, California, the average relative humidity in December is 68%.

How many days does it rain in December?

In December, the rain falls for 11.5 days. Throughout December, 4.69" (119mm) of precipitation is accumulated.

When does it start snowing in Penryn?

December is the first month it typically snows. Throughout December, in the average 0.3 snowfall days, it receives 0.63" (16mm) of snow.

What is the month with the shortest days in Penryn?

With an average of 9h and 30min of daylight, December has the shortest days of the year.

How many hours of daylight does Penryn have in December?

The average day length in December is 9h and 30min.

When are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:04 am and sunset at 4:43 pm. On the last day of the month, sunrise is at 7:23 am and sunset at 4:53 pm PST.

What are the months with the least sunshine?

January and December, with an average of 5.8h of sunshine, are months with the least sunshine.

How long on average sun shines in December in Penryn?

In December, the average sunshine duration is 5.8h.

What is the month with the lowest UV index in Penryn?

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

What is the UV index intensity in December?

In December, the average daily maximum UV index is 3. A UV Index reading of 3 to 5 represents a moderate vulnerability from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Penryn, CA

Average temperature in December - Penryn, CA
  • Average high temperature in December: 53.4°F

The warmest month (with the highest average high temperature) is July (91.9°F).
The month with the lowest average high temperature is December (53.4°F).

  • Average low temperature in December: 39.2°F

The month with the highest average low temperature is July (60.6°F).
The coldest month (with the lowest average low temperature) is December (39.2°F).

Average pressure in December
Penryn, CA

Average pressure in December - Penryn, CA
  • Average pressure in December: 30.13"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).

Average wind speed in December
Penryn, CA

Average wind speed in December - Penryn, CA
  • Average wind speed in December: 4.9mph

The windiest months (with the highest average wind speed) are February and March (5.7mph).
The calmest month (with the lowest average wind speed) is August (4.3mph).

Average humidity in December
Penryn, CA

Average humidity in December - Penryn, CA
  • Average humidity in December: 68%

The month with the highest relative humidity is March (75%).
The month with the lowest relative humidity is July (38%).

Average rainfall in December
Penryn, CA

Average rainfall in December - Penryn, CA
  • Average rainfall in December: 4.69"

The wettest month (with the highest rainfall) is March (5.63").
The driest months (with the least rainfall) are July and August (0.04").

Average rainfall days in December
Penryn, CA

Average rainfall days in December - Penryn, CA
  • Average rainfall days in December: 11.5 days

The month with the highest number of rainy days is March (15.4 days).
The month with the least rainy days is July (1 days).

Average snowfall in December
Penryn, CA

Average snowfall in December - Penryn, CA
  • Average snowfall in December: 0.63"

The month with the highest snowfall is February (1.18").
The months with the least snowfall are January, April, May, June, July, August, September, October and November (0").

Average snowfall days in December
Penryn, CA

Average snowfall days in December - Penryn, CA
  • Average snowfall days in December: 0.3 days

The month with the highest number of snowfall days is February (0.6 days).
The months with the least snowfall days are January, April, May, June, July, August, September, October and November (0 days).

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

Average daylight in December / Average sunshine in December - Penryn, CA
  • Average daylight in December: 9h and 3min

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 5min

The month with the most sunshine is July (Average sunshine: 12h and 6min).
The months with the least sunshine are January and December (Average sunshine: 5h and 48min).

Average sunshine days in December
Penryn, CA

Average sunshine days in December - Penryn, CA
  • Average sunshine days in December: 18.7 days

The month with the most sunshine days is July (29.6 days).
The month with the least sunshine days is March (14.6 days).

Average UV index in December
Penryn, CA

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

The months with the highest UV index are June and July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 3).

Average cloud cover in December
Penryn, CA

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

The month with the most cloud cover is March (Cloud cover 41).
The month with the least cloud cover is July (Cloud cover 4).

Average visibility in December
Penryn, CA

Average visibility in December - Penryn, 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).

Penryn, California, USA

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