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
San Francisco's weather in January indicates an average high-temperature of a still warm 27.3°C (81.1°F), nearly consistent with the 26.5°C (79.7°F) of December. An average minimum temperature of 16.8°C (62.2°F) marks the month of January.Heat index
For most parts of January, the heat index is estimated at a hot 30°C (86°F). Unrelenting activity during exposure could cause fatigue and potentially lead to heat cramps.Note that heat index values are valued for light wind and location in the shade. Direct sunshine exposure could raise heat index values by as much as 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'feels like', melds the effects of warmth and moisture to generate a feeling of heat. The individual's impression of temperature can be shaped by additional aspects such as metabolic variations, physical activity, and clothing. Consider the fact that direct sun exposure can influence how hot one feels, potentially raising the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially vital to children. Young individuals usually face more risks than adults due to their lower sweat production. Their large skin surface area relative to their tiny bodies and high heat production from their activities adds to their risk.
Humidity
In San Francisco, the average relative humidity in January is 75%.Rainfall
In San Francisco, in January, during 11.3 rainfall days, 21mm (0.83") of precipitation is typically accumulated. Throughout the year, there are 272 rainfall days, and 2217mm (87.28") of precipitation is accumulated.Daylight
The average length of the day in January is 11h and 37min.On the first day of January in San Francisco, sunrise is at 05:53 and sunset at 17:26. On the last day of the month, sunrise is at 05:58 and sunset at 17:40 CST.
Sunshine
The average sunshine in January in San Francisco is 8.3h.UV index
January through April, June, July, September, October and December, with an average maximum UV index of 6, are months with the highest UV index in San Francisco. A UV Index reading of 6 to 7 represents a high health hazard from unprotected exposure to Sun's UV rays for the ordinary person.Note: The daily maximum UV index of 6 in January interprets into the following advice:
Deflect overexposure. Sun protection is a necessity. Stay in the shade and avoid direct Sun exposure from 10 a.m. to 4 p.m., a time when UV radiation is at its strongest, and remember that parasols or canopies do not offer full protection. Employ a wide-brim hat for potent defense against up to 50% of UV rays.
Frequently asked questions
What is the average January temperature in San Francisco?
What is the average humidity in January in San Francisco?
How many days does it rain in January in San Francisco?
What is the average length of the day in January in San Francisco?
When are sunrise and sunset in January in San Francisco?
How many hours of sunshine does San Francisco have in January?
When is the highest UV index in San Francisco?
What is the UV index reading in January in San Francisco?
Average temperature in January
San Francisco, Costa Rica
- Average high temperature in January: 27.3°C
The warmest months (with the highest average high temperature) are March and April (29.7°C).
The month with the lowest average high temperature is October (25.4°C).
- Average low temperature in January: 16.8°C
The month with the highest average low temperature is May (19.8°C).
The coldest month (with the lowest average low temperature) is January (16.8°C).
Average pressure in January
San Francisco, Costa Rica
- Average pressure in January: 1012.1mbar
The month with the highest atmospheric pressure is January (1012.1mbar).
The month with the lowest atmospheric pressure is October (1010.7mbar).
Average wind speed in January
San Francisco, Costa Rica
- Average wind speed in January: 10.5km/h
The windiest month (with the highest average wind speed) is February (10.6km/h).
The calmest month (with the lowest average wind speed) is September (3.8km/h).
Average humidity in January
San Francisco, Costa Rica
- Average humidity in January: 75%
The month with the highest relative humidity is October (89%).
The month with the lowest relative humidity is March (70%).
Average rainfall in January
San Francisco, Costa Rica
- Average rainfall in January: 21mm
The wettest month (with the highest rainfall) is October (396mm).
The driest month (with the least rainfall) is February (17mm).
Average rainfall days in January
San Francisco, Costa Rica
- Average rainfall days in January: 11.3 days
The month with the highest number of rainy days is October (30.2 days).
The month with the least rainy days is February (10.3 days).
Average daylight in January /
Average sunshine in January
San Francisco, Costa Rica
- Average daylight in January: 11h and 4min
The month with the longest days is June (Average daylight: 12h and 42min).
The month with the shortest days is December (Average daylight: 11h and 36min).
- Average sunshine in January: 8h and 2min
The month with the most sunshine is March (Average sunshine: 9h and 24min).
The month with the least sunshine is October (Average sunshine: 7h and 0min).
Average sunshine days in January
San Francisco, Costa Rica
- Average sunshine days in January: 16.7 days
The month with the most sunshine days is January (16.7 days).
The month with the least sunshine days is September (0.5 days).
Average UV index in January
San Francisco, Costa Rica
- Average UV index in January: 6
The months with the highest UV index are January, February, March, April, June, July, September, October and December (UV index 6).
The months with the lowest UV index are May, August and November (UV index 5).
Average cloud cover in January
San Francisco, Costa Rica
- Average cloud cover in January: 23
The month with the most cloud cover is October (Cloud cover 54).
The month with the least cloud cover is February (Cloud cover 19).
Average visibility in January
San Francisco, Costa Rica
- Average visibility in January: 9km
The months with the highest visibility are February and March (10km).
The months with the lowest visibility are August, September, October and November (7km).
San Francisco, Costa Rica
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