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 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
December, with average temperatures reaching a high of 63.1°F (17.3°C) and a low of 49.5°F (9.7°C), is the coldest month.Humidity
The average relative humidity in December is 59%.Rainfall
December is the month with the most rainfall. Rain falls for 6.7 days and accumulates 1.85" (47mm) of precipitation.Daylight
The month with the shortest days is December, with an average of 10h and 0min of daylight.On the first day of December, sunrise is at 6:37 am and sunset at 4:42 pm. On the last day of the month, sunrise is at 6:55 am and sunset at 4:52 pm PST.
Sunshine
December has the least sunshine of the year, with an average of 6.6h of sunshine.UV index
January through March, November and December, with an average maximum UV index of 4, are months with the lowest UV index. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for ordinary individuals.Note: The maximum UV index of 4 during December translates into these guidelines:
Exercise care. People with light skin might get burns in fewer than 30 minutes. Considering the Sun's intensity during midday, it's wise to minimize direct exposure. Employ a hat with a wide brim for robust protection, cutting UV exposure by half.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the coldest time of year?
What is the usual temperature for Portola Hills in December?
What is the average humidity in December?
What is the rainiest month in Portola Hills?
How many days does it rain in December?
What is the month with the shortest days?
How many hours of daylight does Portola Hills have in December?
When are sunrise and sunset in December?
What is the month with the least sunshine?
How long on average sun shines in December?
What are the months with the lowest UV index?
What is the UV index intensity in December?
Average temperature in December
Portola Hills, CA
- Average high temperature in December: 63.1°F
The warmest month (with the highest average high temperature) is August (82°F).
The month with the lowest average high temperature is December (63.1°F).
- Average low temperature in December: 49.5°F
The month with the highest average low temperature is August (64.4°F).
The coldest month (with the lowest average low temperature) is February (48.7°F).
Average pressure in December
Portola Hills, CA
- Average pressure in December: 30.07"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The months with the lowest atmospheric pressure are June and September (29.88"Hg).
Average wind speed in December
Portola Hills, CA
- Average wind speed in December: 5mph
The windiest months (with the highest average wind speed) are April and May (5.7mph).
The calmest months (with the lowest average wind speed) are August and September (4.5mph).
Average humidity in December
Portola Hills, CA
- Average humidity in December: 59%
The months with the highest relative humidity are May and June (69%).
The month with the lowest relative humidity is November (55%).
Average rainfall in December
Portola Hills, CA
- Average rainfall in December: 1.85"
The wettest month (with the highest rainfall) is December (1.85").
The driest month (with the least rainfall) is June (0.08").
Average rainfall days in December
Portola Hills, CA
- Average rainfall days in December: 6.7 days
The month with the highest number of rainy days is March (8.1 days).
The month with the least rainy days is June (2 days).
Average daylight in December /
Average sunshine in December
Portola Hills, CA
- Average daylight in December: 10h and 0min
The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 10h and 0min).
- Average sunshine in December: 6h and 4min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 36min).
Average sunshine days in December
Portola Hills, CA
- Average sunshine days in December: 22.5 days
The months with the most sunshine days are January and October (24.2 days).
The month with the least sunshine days is May (19.3 days).
Average UV index in December
Portola Hills, CA
- Average UV index in December: 4
The months with the highest UV index are June, July, August and September (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 4).
Average cloud cover in December
Portola Hills, CA
- Average cloud cover in December: 24
The months with the most cloud cover are March and December (Cloud cover 24).
The month with the least cloud cover is August (Cloud cover 6).
Average visibility in December
Portola Hills, 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).
Portola Hills, California, USA
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