Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
The month of December sees the lowest average temperatures, reaching 37.2°F (2.9°C) at the peak and 21.6°F (-5.8°C) at the low.Humidity
In Portola, the average relative humidity in December is 79%.Rainfall
In Portola, during December, the rain falls for 6.8 days and regularly aggregates up to 3.66" (93mm) of precipitation. Throughout the year, in Portola, there are 80.1 rainfall days, and 22.95" (583mm) of precipitation is accumulated.Snowfall
Months with snowfall in Portola are January through June, September through December. The month with the most snowfall is December, when snow falls for 12.8 days and typically aggregates up to 22.52" (572mm) of snow.Daylight
With an average of 9h and 24min of daylight, December has the shortest days of the year in Portola.On the first day of December, sunrise is at 7:04 am and sunset at 4:37 pm. On the last day of the month, sunrise is at 7:23 am and sunset at 4:47 pm PST.
Sunshine
In December, the average sunshine in Portola is 5.2h.UV index
In December, the average daily maximum UV index is 2. A UV Index value of 2, and less, symbolizes a low threat to health from unprotected exposure to Sun's UV rays for the average person.Note: The maximum daily UV index of 2 in December converts into the following recommendations:
While most people can stay under the sun for an hour without burning, children must always be guarded against sun exposure. Considering the strength of solar radiation at midday, one should avoid direct Sun exposure. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes. Mark this! Snow reflection can nearly double the UV radiation intensity from the Sun.
Frequently asked questions
What is the coldest month in Portola?
How cold is December in Portola?
What is the average humidity in December in Portola?
How many days does it rain in December in Portola?
When does it snow the most in Portola?
How many days does it snow in December in Portola?
What is the month with the shortest days in Portola?
How many hours of daylight does Portola have in December?
When are sunrise and sunset in December in Portola?
How many hours of sunshine does Portola have in December?
What is the UV index reading in December in Portola?
Average temperature in December
Portola, CA
- Average high temperature in December: 37.2°F
The warmest month (with the highest average high temperature) is July (82.9°F).
The month with the lowest average high temperature is December (37.2°F).
- Average low temperature in December: 21.6°F
The month with the highest average low temperature is July (47.5°F).
The coldest month (with the lowest average low temperature) is December (21.6°F).
Average pressure in December
Portola, CA
- Average pressure in December: 30.16"Hg
The month with the highest atmospheric pressure is January (30.19"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in December
Portola, CA
- Average wind speed in December: 5.7mph
The windiest month (with the highest average wind speed) is March (6.6mph).
The calmest months (with the lowest average wind speed) are August and September (5.2mph).
Average humidity in December
Portola, CA
- Average humidity in December: 79%
The months with the highest relative humidity are January and March (81%).
The months with the lowest relative humidity are July and August (40%).
Average rainfall in December
Portola, CA
- Average rainfall in December: 3.66"
The wettest month (with the highest rainfall) is March (4.02").
The driest month (with the least rainfall) is August (0.2").
Average rainfall days in December
Portola, CA
- Average rainfall days in December: 6.8 days
The month with the highest number of rainy days is May (11.8 days).
The month with the least rainy days is July (3.3 days).
Average snowfall in December
Portola, CA
- Average snowfall in December: 22.52"
The month with the highest snowfall is December (22.52").
The months with the least snowfall are July and August (0").
Average snowfall days in December
Portola, CA
- Average snowfall days in December: 12.8 days
The month with the highest number of snowfall days is March (14.7 days).
The months with the least snowfall days are July and August (0 days).
Average daylight in December /
Average sunshine in December
Portola, CA
- Average daylight in December: 9h and 2min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in December: 5h and 1min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 5h and 0min).
Average sunshine days in December
Portola, CA
- Average sunshine days in December: 15.5 days
The month with the most sunshine days is August (26 days).
The month with the least sunshine days is March (11.8 days).
Average UV index in December
Portola, CA
- Average UV index in December: 2
The months with the highest UV index are June, July and August (UV index 5).
The month with the lowest UV index is November (UV index 1).
Average cloud cover in December
Portola, CA
- Average cloud cover in December: 45
The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 7).
Average visibility in December
Portola, CA
- Average visibility in December: 4mi
The months with the highest visibility are May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and December (4mi).
Portola, California, USA
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