January weather forecast
San Francisco, CA

A beautiful dusk view of the Golden Gate Bridge in San Francisco, California
A beautiful dusk view of the Golden Gate Bridge in San Francisco, California

Weather in January

January, the same as December, in San Francisco, California, is a moderate winter month, with an average temperature fluctuating between 56.3°F (13.5°C) and 45.9°F (7.7°C).

Temperature

In San Francisco, California, the average high-temperature in January is essentially the same as in December - a still mild 56.3°F (13.5°C). In San Francisco, the average low-temperature is 45.9°F (7.7°C).

Humidity

The average relative humidity in January in San Francisco, California, is 73%.

Rainfall

In San Francisco, it is raining for 8.2 days, with typically 1.02" (26mm) of accumulated precipitation. Throughout the year, in San Francisco, there are 58.6 rainfall days, and 6.46" (164mm) of precipitation is accumulated.

Ocean temperature

In San Francisco, in January, the average water temperature is 53.2°F (11.8°C).
Note: At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

Daylight

The average length of the day in January in San Francisco is 9h and 55min.
On the first day of January in San Francisco, sunrise is at 7:25 am and sunset at 5:01 pm. On the last day of the month, sunrise is at 7:14 am and sunset at 5:31 pm PST.

Sunshine

The average sunshine in January in San Francisco is 6.1h.

UV index

January, February, November and December, with an average maximum UV index of 3, are months with the lowest UV index in San Francisco, California. A UV Index estimate of 3 to 5 represents a moderate threat to health from unprotected exposure to Sun's UV rays for the average person.
Note: The average daily UV index of 3 in January transform into the following instructions:
Take precautions - Protection against skin and eye damage is obliged. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.
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FAQ

What is the temperature in January in San Francisco?

In January, in San Francisco, the average high-temperature is 56.3°F (13.5°C), and the average low-temperature is 45.9°F (7.7°C).

What is the average humidity in January in San Francisco?

The average relative humidity in January in San Francisco, California, is 73%.

How many days does it rain in January in San Francisco?

In San Francisco, during January, the rain falls for 8.2 days and regularly aggregates up to 1.02" (26mm) of precipitation.

How cold is the water in January in San Francisco?

In San Francisco, California, in January, the average water temperature is 53.2°F (11.8°C). At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

What is the average length of the day in January in San Francisco?

In January, the average day length is 9h and 55min.

When is the sunrise / sunset in January in San Francisco?

In January, on the first day of the month, sunrise is at 7:25 am and sunset at 5:01 pm. On the last day of the month, in San Francisco, California, sunrise is at 7:14 am and sunset at 5:31 pm PST.

How long on average sun shines in January in San Francisco?

The average sunshine duration in January is 6.1h.

What is the month with the lowest UV index in San Francisco?

January, February, November and December, with an average maximum UV index of 3, are months with the lowest UV index.

How high is the UV index in January in San Francisco?

The average daily maximum UV index in January in San Francisco is 3. A UV Index reading of 3 to 5 represents a moderate vulnerability from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in January
San Francisco, CA

Average temperature in January - San Francisco, CA
  • Average high temperature in January: 56.3°F

The warmest month (with the highest average high temperature) is September (73.2°F).
The month with the lowest average high temperature is December (55.8°F).

  • Average low temperature in January: 45.9°F

The month with the highest average low temperature is September (56.7°F).
The coldest months (with the lowest average low temperature) are January and December (45.9°F).

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Average pressure in January
San Francisco, CA

Average pressure in January - San Francisco, CA
  • Average pressure in January: 30.13"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).

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Average wind speed in January
San Francisco, CA

Average wind speed in January - San Francisco, CA
  • Average wind speed in January: 5.8mph

The windiest month (with the highest average wind speed) is May (7.6mph).
The calmest month (with the lowest average wind speed) is November (5.5mph).

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Average humidity in January
San Francisco, CA

Average humidity in January - San Francisco, 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 (67%).

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Average rainfall in January
San Francisco, CA

Average rainfall in January - San Francisco, CA
  • Average rainfall in January: 1.02"

The wettest month (with the highest rainfall) is February (1.38").
The driest months (with the least rainfall) are July, August and September (0.08").

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Average rainfall days in January
San Francisco, CA

Average rainfall days in January - San Francisco, CA
  • Average rainfall days in January: 8.2 days

The month with the highest number of rainy days is March (9.3 days).
The month with the least rainy days is June (1.9 days).

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Average sea temperature in January
San Francisco, CA

Average sea temperature in January - San Francisco, CA
  • Average sea temperature in January: 53.2°F

The best month for swimming (with the highest average sea temperature) is September (57.3°F).
The coldest months (with the lowest average sea temperature) are April and June (53°F).

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Average daylight in January /
Average sunshine in January
San Francisco, CA

Average daylight in January / Average sunshine in January - San Francisco, CA
  • Average daylight in January: 9h and 55min

The month with the longest days is June (Average daylight: 14h and 44min).
The month with the shortest days is December (Average daylight: 9h and 36min).

  • Average sunshine in January: 6h and 6min

The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).

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Average sunshine days in January
San Francisco, CA

Average sunshine days in January - San Francisco, CA
  • Average sunshine days in January: 22 days

The month with the most sunshine days is October (25.8 days).
The month with the least sunshine days is March (20.8 days).

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Average UV index in January
San Francisco, CA

Average UV index in January - San Francisco, CA
  • Average UV index in January: 3

The months with the highest UV index are April, June, July, August and September (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 3).

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Average cloud cover in January
San Francisco, CA

Average cloud cover in January - San Francisco, CA
  • Average cloud cover in January: 33

The month with the most cloud cover is March (Cloud cover 36).
The months with the least cloud cover are July and September (Cloud cover 14).

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Average visibility in January
San Francisco, CA

Average visibility in January - San Francisco, 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).

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