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
The start of January sees the average high-temperature at a still mild 56.8°F (13.8°C), showing little difference from December's 55.8°F (13.2°C). During January, Foster City records an average temperature of 46.9°F (8.3°C) at night.Humidity
In Foster City, California, the average relative humidity in January is 73%.Rainfall
In Foster City, in January, during 4.4 rainfall days, 0.31" (8mm) of precipitation is typically accumulated. In Foster City, during the entire year, the rain falls for 32.6 days and collects up to 2.13" (54mm) of precipitation.Daylight
In January, the average length of the day in Foster City is 9h and 55min.On the first day of January in Foster City, sunrise is at 7:23 am and sunset at 5:01 pm. On the last day of the month, sunrise is at 7:13 am and sunset at 5:31 pm PST.
Sunshine
The average sunshine in January is 6.2h.UV index
The average daily maximum UV index in January is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.Note: An average maximum UV index of 4 in January leads to these recommendations:
Adopt protective measures - Requirement to safeguard skin and eyes from harm exists. To prevent harmful UV exposure, minimize direct contact with the Sun around midday. Stay sun-safe with clothing that is both closely woven and worn loosely.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in January?
What is the average humidity in January?
How many days does it rain in January?
How many hours of daylight does Foster City have in January?
What time are sunrise and sunset in January?
How many hours of sunshine does Foster City have in January?
What is the UV index intensity in January?
Average temperature in January
Foster City, CA
- Average high temperature in January: 56.8°F
The warmest months (with the highest average high temperature) are August and September (71.2°F).
The month with the lowest average high temperature is December (55.8°F).
- Average low temperature in January: 46.9°F
The month with the highest average low temperature is September (56.7°F).
The coldest month (with the lowest average low temperature) is January (46.9°F).
Average pressure in January
Foster City, 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
Foster City, CA
- Average wind speed in January: 6.2mph
The windiest month (with the highest average wind speed) is April (8mph).
The calmest months (with the lowest average wind speed) are August, September and October (5.9mph).
Average humidity in January
Foster City, CA
- Average humidity in January: 73%
The months with the highest relative humidity are March and August (76%).
The months with the lowest relative humidity are October and November (70%).
Average rainfall in January
Foster City, CA
- Average rainfall in January: 0.31"
The wettest month (with the highest rainfall) is February (0.55").
The driest months (with the least rainfall) are June, July and August (0").
Average rainfall days in January
Foster City, CA
- Average rainfall days in January: 4.4 days
The month with the highest number of rainy days is March (6.8 days).
The month with the least rainy days is July (0.3 days).
Average daylight in January /
Average sunshine in January
Foster City, CA
- Average daylight in January: 9h and 5min
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 1min
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
Foster City, CA
- Average sunshine days in January: 25 days
The month with the most sunshine days is July (30.4 days).
The month with the least sunshine days is February (23.3 days).
Average UV index in January
Foster City, 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 and December (UV index 3).
Average cloud cover in January
Foster City, CA
- Average cloud cover in January: 32
The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 11).
Average visibility in January
Foster City, 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).
Foster City, California, USA
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