Contents
- Weather in January
- Frequently asked questions
- Average temperature in January
- Average pressure in January
- Average wind speed in January
- Average humidity in January
- Average rainfall in January
- Average rainfall days in January
- Average daylight in January
- Average sunshine in January
- Average sunshine days in January
- Average UV index in January
- Average cloud cover in January
- Average visibility in January
Weather in January
Temperature
Portola Hills's weather in January, with an average high-temperature of a still refreshing 65.1°F (18.4°C), subtly shifts from December's 63.1°F (17.3°C). Nighttime temperature experiences an average drop to a cool 50°F (10°C) in January.Humidity
The average relative humidity in January is 57%.Rainfall
In Portola Hills, in January, during 5.6 rainfall days, 1.3" (33mm) of precipitation is typically accumulated. In Portola Hills, during the entire year, the rain falls for 65.4 days and collects up to 9.17" (233mm) of precipitation.Daylight
In Portola Hills, the average length of the day in January is 10h and 13min.On the first day of the month, sunrise is at 6:55 am and sunset at 4:52 pm. On the last day of January, sunrise is at 6:47 am and sunset at 5:20 pm PST.
Sunshine
The average sunshine in January is 6.8h.UV index
The months with the lowest UV index are January through March, November and December, with an average maximum UV index of 4. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for ordinary individuals.Note: The daily high UV index of 4 during January translates into the following recommendations:
Ensure safety - Imperative it is to shield skin and eyes from damage. Around midday, solar radiation is most harmful; hence, exposure should be limited. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in January?
What is the average humidity in January?
How much does it rain in January?
What is the average length of the day in January?
What time are sunrise and sunset in January?
How many hours of sunshine does Portola Hills have in January?
What are the months with the lowest UV index?
What is the UV index reading in January?
Average temperature in January
Portola Hills, CA
- Average high temperature in January: 65.1°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 January: 50°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 January
Portola Hills, CA
- Average pressure in January: 30.1"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 January
Portola Hills, CA
- Average wind speed in January: 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 January
Portola Hills, CA
- Average humidity in January: 57%
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 January
Portola Hills, CA
- Average rainfall in January: 1.3"
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 January
Portola Hills, CA
- Average rainfall days in January: 5.6 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 January /
Average sunshine in January
Portola Hills, CA
- Average daylight in January: 10h and 1min
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 January: 6h and 5min
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 January
Portola Hills, CA
- Average sunshine days in January: 24.2 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 January
Portola Hills, CA
- Average UV index in January: 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 January
Portola Hills, CA
- Average cloud cover in January: 22
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 January
Portola Hills, CA
- Average visibility in January: 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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