January weather forecastCastro Valley, CA
January
Weather in January
January, the same as December, in Castro Valley, California, is a moderate winter month, with an average temperature varying between 43.7°F (6.5°C) and 57°F (13.9°C).Temperature
January's weather records an average high-temperature of a still moderate 57°F (13.9°C), showing little deviation from December. Throughout January, an average low-temperature of 43.7°F (6.5°C) is experienced in Castro Valley.Humidity
The average relative humidity in January is 72%.Rainfall
In Castro Valley, during January, the rain falls for 9.3 days and regularly aggregates up to 1.89" (48mm) of precipitation. Throughout the year, in Castro Valley, California, there are 69.2 rainfall days, and 11.1" (282mm) of precipitation is accumulated.Daylight
In Castro Valley, the average length of the day in January is 9h and 55min.On the first day of the month, sunrise is at 7:23 am and sunset at 5:00 pm. On the last day of January, in Castro Valley, sunrise is at 7:12 am and sunset at 5:30 pm PST.
Sunshine
The average sunshine in January in Castro Valley is 6.3h.UV index
The months with the lowest UV index in Castro Valley are January, February, November and December, with an average maximum UV index of 3. A UV Index of 3 to 5 symbolizes a medium health hazard from unsafe exposure to UV radiation for the average person.Note: The UV index of 3 during January leads to these advisories:
Proceed with care. Light skin individuals may be exposed to burns in fewer than 30 minutes. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in January
Castro Valley, CA
- Average high temperature in January: 57°F
The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is December (55.9°F).
- Average low temperature in January: 43.7°F
The month with the highest average low temperature is August (56.5°F).
The coldest months (with the lowest average low temperature) are January and December (43.7°F).
Average pressure in January
Castro Valley, CA
- Average pressure in January: 30.14"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).
Average wind speed in January
Castro Valley, CA
- Average wind speed in January: 4.8mph
The windiest month (with the highest average wind speed) is May (6.6mph).
The calmest month (with the lowest average wind speed) is November (4.6mph).
Average humidity in January
Castro Valley, CA
- Average humidity in January: 72%
The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is September (61%).
Average rainfall in January
Castro Valley, CA
- Average rainfall in January: 1.89"
The wettest month (with the highest rainfall) is February (2.28").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in January
Castro Valley, CA
- Average rainfall days in January: 9.3 days
The month with the highest number of rainy days is March (12.4 days).
The month with the least rainy days is August (0.9 days).
Average daylight in January /
Average sunshine in January
Castro 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 6min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).
Average sunshine days in January
Castro Valley, CA
- Average sunshine days in January: 20.5 days
The month with the most sunshine days is August (28.9 days).
The month with the least sunshine days is March (17.3 days).
Average UV index in January
Castro Valley, CA
- Average UV index in January: 3
The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in January
Castro Valley, CA
- Average cloud cover in January: 31
The months with the most cloud cover are March and December (Cloud cover 34).
The month with the least cloud cover is July (Cloud cover 7).
Average visibility in January
Castro 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).
