January weather forecast and climate
Half Moon Bay, CA

A warm and sunny day on a scenic beach in Half Moon Bay, California
A warm and sunny day on a scenic beach in Half Moon Bay, California

Weather in January

January, like December, is a moderate winter month in Half Moon Bay, California, with average temperature ranging between max 56.1°F (13.4°C) and min 49.1°F (9.5°C).

Temperature

In January, the average high-temperature is relatively the same as in December - a still mild 56.1°F (13.4°C). In Half Moon Bay, the average low-temperature is 49.1°F (9.5°C).

Humidity

In January, the average relative humidity in Half Moon Bay is 74%.

Rainfall

In January, the rain falls for 9.2 days. Throughout January, 1.22" (31mm) of precipitation is accumulated. In Half Moon Bay, California, during the entire year, the rain falls for 76.8 days and collects up to 8.54" (217mm) of precipitation.

Daylight

In January, the average length of the day in Half Moon Bay is 9.9h.

Sunshine

In Half Moon Bay, the average sunshine in January is 6h.

UV index

Months with the lowest UV index are January through May, July, October through December, with an average maximum UV index of 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to the UV radiation for the ordinary person.
Note: The daily maximum UV index of 4 interpret into the following advice:
Take precautions - Protection against the 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. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
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FAQ

What is the temperature in January in Half Moon Bay?

In Half Moon Bay, California, in January, the average high-temperature is 56.1°F (13.4°C), and the average low-temperature is 49.1°F (9.5°C).

What is the average humidity in January in Half Moon Bay?

In January, the average relative humidity in Half Moon Bay is 74%.

How many days does it rain in January in Half Moon Bay?

In Half Moon Bay, during January, the rain falls for 9.2 days and regularly aggregates up to 1.22" (31mm) of precipitation.

What is the average length of the day in January in Half Moon Bay?

In Half Moon Bay, the average length of the day in January is 9.9h.

How many hours of sunshine does Half Moon Bay have in January?

The average sunshine in January in Half Moon Bay, California, is 6h.

What is the month with the lowest UV index in Half Moon Bay?

Months with the lowest UV index in Half Moon Bay, California, are January through May, July, October through December, with an average maximum UV index of 4.

What is the UV index reading in January in Half Moon Bay?

In January, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a medium health risk from the exposure to the Sun's UV radiation.

Average temperature in January
Half Moon Bay, CA

Average temperature in January - Half Moon Bay, CA
  • Average high temperature in January: 56.1°F

The warmest month (with the highest average high temperature) is September (66.9°F).
The month with the lowest average high temperature is December (55.6°F).

  • Average low temperature in January: 49.1°F

The month with the highest average low temperature is September (56.7°F).
The coldest month (with the lowest average low temperature) is February (48.7°F).

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Average pressure in January
Half Moon Bay, CA

Average pressure in January - Half Moon Bay, 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
Half Moon Bay, CA

Average wind speed in January - Half Moon Bay, CA
  • Average wind speed in January: 7.5mph

The windiest month (with the highest average wind speed) is April (9.6mph).
The calmest month (with the lowest average wind speed) is August (6.6mph).

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Average humidity in January
Half Moon Bay, CA

Average humidity in January - Half Moon Bay, CA
  • Average humidity in January: 74%

The month with the highest relative humidity is August (82%).
Months with the lowest relative humidity are November and December (72%).

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Average rainfall in January
Half Moon Bay, CA

Average rainfall in January - Half Moon Bay, CA
  • Average rainfall in January: 1.22"

The wettest month (with the highest rainfall) is February (1.61").
The driest months (with the least rainfall) are June and July (0.12").

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Average rainfall days in January
Half Moon Bay, CA

Average rainfall days in January - Half Moon Bay, CA
  • Average rainfall days in January: 9.2 days

The month with the highest number of rainy days is March (10.8 days).
The month with the least rainy days is June (3 days).

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Average daylight in January /
Average sunshine in January
Half Moon Bay, CA

Average daylight in January / Average sunshine in January - Half Moon Bay, 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: 11.4h).
The month with the least sunshine is December (Average sunshine: 5.7h).

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Average sunshine days in January
Half Moon Bay, CA

Average sunshine days in January - Half Moon Bay, CA
  • Average sunshine days in January: 20.8 days

The month with the most sunshine days is October (24.6 days).
Months with the least sunshine days are March and August (18.8 days).

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Average UV index in January
Half Moon Bay, CA

Average UV index in January - Half Moon Bay, CA
  • Average UV index in January: 4

Months with the highest UV index are June, August and September (UV index 5).
Months with the lowest UV index are January, February, March, April, May, July, October, November and December (UV index 4).

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Average cloud cover in January
Half Moon Bay, CA

Average cloud cover in January - Half Moon Bay, CA
  • Average cloud cover in January: 34

The month with the most cloud cover is March (Cloud cover 38).
The month with the least cloud cover is September (Cloud cover 18).

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Average visibility in January
Half Moon Bay, CA

Average visibility in January - Half Moon Bay, 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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