January weather forecastPortola Valley, CA
January
Weather in January
January, the same as December, in Portola Valley, California, is another mild winter month, with an average temperature varying between 56.7°F (13.7°C) and 46.4°F (8°C).Temperature
With January's advent, Portola Valley sees an average high-temperature of a still mild 56.7°F (13.7°C), subtly shifted from December's 55.8°F (13.2°C). Throughout January, Portola Valley registers a consistent average low-temperature of 46.4°F (8°C).Humidity
The average relative humidity in January in Portola Valley is 73%.Rainfall
In Portola Valley, in January, it is raining for 7.8 days, with typically 0.67" (17mm) of accumulated precipitation. Throughout the year, in Portola Valley, California, there are 57.5 rainfall days, and 4.76" (121mm) of precipitation is accumulated.Daylight
The average length of the day in January in Portola Valley, California, is 9h and 56min.On the first day of the month, sunrise is at 7:23 am and sunset at 5:01 pm. On the last day of January, sunrise is at 7:12 am and sunset at 5:31 pm PST.
Sunshine
In January, the average sunshine is 6.3h.UV index
In January, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for the average person.Note: In January, a regular UV index of 4 translates into these guidelines:
Be vigilant - Preventing sunburn is recommended. The solar radiation around mid-day is intense; avoid the Sun and stay safe. Arm yourself against UV rays' harm with protective apparel and UV-filtering shades.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in January
Portola Valley, CA
- Average high temperature in January: 56.7°F
The warmest month (with the highest average high temperature) is August (73°F).
The month with the lowest average high temperature is December (55.8°F).
- Average low temperature in January: 46.4°F
The months with the highest average low temperature are August and September (56.7°F).
The coldest months (with the lowest average low temperature) are January and February (46.4°F).
Average pressure in January
Portola Valley, CA
- Average pressure in January: 30.13"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is September (29.92"Hg).
Average wind speed in January
Portola Valley, CA
- Average wind speed in January: 6mph
The windiest month (with the highest average wind speed) is April (7.6mph).
The calmest month (with the lowest average wind speed) is August (5.5mph).
Average humidity in January
Portola Valley, CA
- Average humidity in January: 73%
The month with the highest relative humidity is March (76%).
The month with the lowest relative humidity is October (68%).
Average rainfall in January
Portola Valley, CA
- Average rainfall in January: 0.67"
The wettest month (with the highest rainfall) is February (0.98").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in January
Portola Valley, CA
- Average rainfall days in January: 7.8 days
The month with the highest number of rainy days is March (10.6 days).
The month with the least rainy days is June (0.9 days).
Average daylight in January /
Average sunshine in January
Portola Valley, CA
- Average daylight in January: 9h and 54min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in January: 6h and 18min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).
Average sunshine days in January
Portola Valley, CA
- Average sunshine days in January: 21.8 days
The months with the most sunshine days are June and July (26.3 days).
The month with the least sunshine days is March (18.3 days).
Average UV index in January
Portola Valley, CA
- Average UV index in January: 4
The months with the highest UV index are June, July, August and September (UV index 5).
The months with the lowest UV index are February, November and December (UV index 3).
Average cloud cover in January
Portola Valley, CA
- Average cloud cover in January: 31
The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 9).
Average visibility in January
Portola Valley, 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).
