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
In Altadena, the month of December registers the lowest temperatures, averaging 61°F (16.1°C) at the peak and 45.5°F (7.5°C) at the lowest.Humidity
In Altadena, the average relative humidity in December is 52%.Rainfall
In December, the rain falls for 6.2 days. Throughout December, 1.77" (45mm) of precipitation is accumulated. In Altadena, California, during the entire year, the rain falls for 52 days and collects up to 8.82" (224mm) of precipitation.Daylight
The month with the shortest days in Altadena, California, is December, with an average of 9h and 54min of daylight.On the first day of December, sunrise is at 6:40 am and sunset at 4:42 pm. On the last day of the month, sunrise is at 6:58 am and sunset at 4:53 pm PST.
Sunshine
The months with the least sunshine in Altadena are February and December, with an average of 6.9h of sunshine.UV index
December is the month with the lowest UV index, with an average maximum UV index of 3. A UV Index estimate of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for the ordinary person.Note: The maximum UV index of 3 during December leads to these instructions:
Exercise prevention - Protecting skin and eyes from harm is required. Being in direct Sun during midday can be harmful due to intense solar radiation; take precautions. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes.
Frequently asked questions
What is the coldest time of year in Altadena?
What are the temperatures in Altadena in December?
What is the average humidity in December in Altadena?
How many days does it rain in December in Altadena?
What is the month with the shortest days in Altadena?
What is the average length of the day in December in Altadena?
What time are sunrise and sunset in December in Altadena?
What are the months with the least sunshine in Altadena?
How long on average sun shines in December in Altadena?
What is the month with the lowest UV index in Altadena?
What is the UV index intensity in December in Altadena?
Average temperature in December
Altadena, CA
- Average high temperature in December: 61°F
The warmest month (with the highest average high temperature) is August (86.2°F).
The month with the lowest average high temperature is December (61°F).
- Average low temperature in December: 45.5°F
The month with the highest average low temperature is August (64.4°F).
The coldest month (with the lowest average low temperature) is December (45.5°F).
Average pressure in December
Altadena, CA
- Average pressure in December: 30.08"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in December
Altadena, CA
- Average wind speed in December: 5.5mph
The windiest month (with the highest average wind speed) is April (5.8mph).
The calmest month (with the lowest average wind speed) is September (4.4mph).
Average humidity in December
Altadena, CA
- Average humidity in December: 52%
The months with the highest relative humidity are March, May and June (56%).
The month with the lowest relative humidity is November (46%).
Average rainfall in December
Altadena, CA
- Average rainfall in December: 1.77"
The wettest month (with the highest rainfall) is February (1.81").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in December
Altadena, CA
- Average rainfall days in December: 6.2 days
The month with the highest number of rainy days is March (7.5 days).
The month with the least rainy days is June (1.3 days).
Average daylight in December /
Average sunshine in December
Altadena, CA
- Average daylight in December: 9h and 5min
The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).
- Average sunshine in December: 6h and 5min
The months with the most sunshine are June and July (Average sunshine: 12h and 6min).
The months with the least sunshine are February and December (Average sunshine: 6h and 54min).
Average sunshine days in December
Altadena, CA
- Average sunshine days in December: 23.5 days
The month with the most sunshine days is June (27.2 days).
The month with the least sunshine days is February (21.3 days).
Average UV index in December
Altadena, CA
- Average UV index in December: 3
The months with the highest UV index are June, July, August and September (UV index 6).
The month with the lowest UV index is December (UV index 3).
Average cloud cover in December
Altadena, CA
- Average cloud cover in December: 21
The month with the most cloud cover is March (Cloud cover 22).
The month with the least cloud cover is August (Cloud cover 5).
Average visibility in December
Altadena, 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).
Altadena, California, USA
Weather forecast for your location
2. Allow the app to use your location
