January weather forecast and climate
San Bruno, CA

Weather in January

January, the same as December, in San Bruno, California, is a moderate winter month, with average temperature varying between 56.3°F (13.5°C) and 47.8°F (8.8°C).

Temperature

In January, the average high-temperature is essentially the same as in December - a still moderate 56.3°F (13.5°C). In January, the average low-temperature is 47.8°F (8.8°C).

Humidity

In January, the average relative humidity is 73%.

Rainfall

In San Bruno, it is raining for 10.8 days, with typically 2.2" (56mm) of accumulated precipitation. Throughout the year, there are 81.8 rainfall days, and 13.46" (342mm) of precipitation is accumulated.

Daylight

The average length of the day in January is 9.9h.

Sunshine

In January, the average sunshine is 6h.

UV index

In San Bruno, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a moderate health risk from the exposure to the Sun's UV radiation for the ordinary person.
Note: In January, the average maximum UV index of 4 translate into the following recommendations:
Take precautions - Protection against sunburn is recommended. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
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FAQ

What is the temperature in January in San Bruno?

In January, in San Bruno, California, the average high-temperature is 56.3°F (13.5°C), and the average low-temperature is 47.8°F (8.8°C).

What is the average humidity in January in San Bruno?

In San Bruno, California, the average relative humidity in January is 73%.

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

In San Bruno, California, during January, the rain falls for 10.8 days and regularly aggregates up to 2.2" (56mm) of precipitation.

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

In San Bruno, California, the average length of the day in January is 9.9h.

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

In San Bruno, the average sunshine in January is 6h.

What is the UV index reading in January in San Bruno?

The average daily maximum UV index in January is 4. A UV Index value of 3 to 5 symbolizes a moderate health threat from unsafe exposure to the Sun's UV rays.

Average temperature in January
San Bruno, CA

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

The warmest month (with the highest average high temperature) is September (69.8°F).
The month with the lowest average high temperature is December (55.8°F).

  • Average low temperature in January: 47.8°F

The month with the highest average low temperature is September (56.5°F).
The coldest month (with the lowest average low temperature) is December (47.7°F).

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Average pressure in January
San Bruno, CA

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

The month with the highest atmospheric pressure is January (30.13").
The month with the lowest atmospheric pressure is September (29.92").

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Average wind speed in January
San Bruno, CA

Average wind speed in January - San Bruno, CA
  • Average wind speed in January: 6.7mph

The windiest month (with the highest average wind speed) is April (8.5mph).
The calmest months (with the lowest average wind speed) are August and September (6.3mph).

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Average humidity in January
San Bruno, CA

Average humidity in January - San Bruno, CA
  • Average humidity in January: 73%

The month with the highest relative humidity is August (79%).
Months with the lowest relative humidity are October and November (71%).

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Average rainfall in January
San Bruno, CA

Average rainfall in January - San Bruno, CA
  • Average rainfall in January: 2.2"

The wettest month (with the highest rainfall) is February (2.72").
The driest months (with the least rainfall) are July and August (0.04").

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Average rainfall days in January
San Bruno, CA

Average rainfall days in January - San Bruno, CA
  • Average rainfall days in January: 10.8 days

The month with the highest number of rainy days is March (13.3 days).
Months with the least rainy days are July and August (2.2 days).

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

Average daylight in January / Average sunshine in January - San Bruno, CA
  • Average daylight in January: 9.9h

The month with the longest days is June (Average daylight: 14.7h).
The month with the shortest days is December (Average daylight: 9.6h).

  • Average sunshine in January: 6h

The month with the most sunshine is July (Average sunshine: 11.8h).
The month with the least sunshine is December (Average sunshine: 5.8h).

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Average sunshine days in January
San Bruno, CA

Average sunshine days in January - San Bruno, CA
  • Average sunshine days in January: 19.8 days

The month with the most sunshine days is July (27.3 days).
The month with the least sunshine days is March (16.3 days).

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Average UV index in January
San Bruno, CA

Average UV index in January - San Bruno, CA
  • Average UV index in January: 4

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

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Average cloud cover in January
San Bruno, CA

Average cloud cover in January - San Bruno, CA
  • Average cloud cover in January: 34

The month with the most cloud cover is March (Cloud cover 37).
The month with the least cloud cover is September (Cloud cover 16).

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Average visibility in January
San Bruno, CA

Average visibility in January - San Bruno, CA
  • Average visibility in January: 6mi

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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