December weather forecast and climate
Hayward, CA

The landscape of the famed Verdant Hills in Hayward, California
The landscape of the famed Verdant Hills in Hayward, California

Weather in December

December, the first month of the winter, in Hayward, is still a mild month, with temperature in the range of an average low of 43.7°F (6.5°C) and an average high of 55.9°F (13.3°C).

Temperature

With an average high-temperature of 55.9°F (13.3°C) and an average low-temperature of 43.7°F (6.5°C), December is the coldest month.

Humidity

The average relative humidity in December is 70%.

Rainfall

In December, the rain falls for 10.2 days. Throughout December, 1.81" (46mm) of precipitation is accumulated. In Hayward, California, during the entire year, the rain falls for 69.2 days and collects up to 11.1" (282mm) of precipitation.

Daylight

The month with the shortest days is December, with an average of 9.6h of daylight.

Sunshine

With an average of 5.9h of sunshine, December has the least sunshine of the year.

UV index

Months with the lowest UV index in Hayward are January, February, November and December, with an average maximum UV index of 3. A UV Index reading of 3 to 5 represents a medium vulnerability from the exposure to the Sun's UV radiation for average individuals.
Note: In December, the average maximum UV index of 3 translate into the following recommendations:
Take precautions - Protection against sunburn is recommended. 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 coldest month in Hayward?

With an average high-temperature of 55.9°F (13.3°C) and an average low-temperature of 43.7°F (6.5°C), December is the coldest month.

What is the temperature in December in Hayward?

In December, the average high-temperature is 55.9°F (13.3°C), and the average low-temperature is 43.7°F (6.5°C).

What is the average humidity in December in Hayward?

In Hayward, the average relative humidity in December is 70%.

How many days does it rain in December in Hayward?

In Hayward, California, during December, the rain falls for 10.2 days and regularly aggregates up to 1.81" (46mm) of precipitation.

What is the month with the shortest days in Hayward?

The month with the shortest days in Hayward, California, is December, with an average of 9.6h of daylight.

How many hours of daylight does Hayward have in December?

In Hayward, California, the average length of the day in December is 9.6h.

What is the month with the least sunshine in Hayward?

December has the least sunshine of the year in Hayward, California, with an average of 5.9h of sunshine.

How long on average sun shines in December in Hayward?

In Hayward, the average sunshine in December is 5.9h.

What are the months with the lowest UV index in Hayward?

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 December in Hayward?

The average daily maximum UV index in December in Hayward, California, is 3. A UV Index estimate of 3 to 5 represents a moderate vulnerability from unsafe exposure to the Sun's UV rays.

Average temperature in December
Hayward, CA

Average temperature in December - Hayward, CA
  • Average high temperature in December: 55.9°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 December: 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).

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Average pressure in December
Hayward, CA

Average pressure in December - Hayward, CA
  • Average pressure in December: 30.11"

The month with the highest atmospheric pressure is January (30.14").
Months with the lowest atmospheric pressure are June, August and September (29.92").

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Average wind speed in December
Hayward, CA

Average wind speed in December - Hayward, CA
  • Average wind speed in December: 5.2mph

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).

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Average humidity in December
Hayward, CA

Average humidity in December - Hayward, CA
  • Average humidity in December: 70%

The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is September (61%).

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Average rainfall in December
Hayward, CA

Average rainfall in December - Hayward, CA
  • Average rainfall in December: 1.81"

The wettest month (with the highest rainfall) is February (2.28").
The driest months (with the least rainfall) are July and August (0.04").

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Average rainfall days in December
Hayward, CA

Average rainfall days in December - Hayward, CA
  • Average rainfall days in December: 10.2 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).

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Average daylight in December /
Average sunshine in December
Hayward, CA

Average daylight in December / Average sunshine in December - Hayward, CA
  • Average daylight in December: 9.6h

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 December: 5.9h

The month with the most sunshine is July (Average sunshine: 12.1h).
The month with the least sunshine is December (Average sunshine: 5.9h).

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Average sunshine days in December
Hayward, CA

Average sunshine days in December - Hayward, CA
  • Average sunshine days in December: 19.4 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).

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Average UV index in December
Hayward, CA

Average UV index in December - Hayward, CA
  • Average UV index in December: 3

The month with the highest UV index is June (UV index 6).
Months with the lowest UV index are January, February, November and December (UV index 3).

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Average cloud cover in December
Hayward, CA

Average cloud cover in December - Hayward, CA
  • Average cloud cover in December: 34

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).

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Average visibility in December
Hayward, CA

Average visibility in December - Hayward, CA
  • Average visibility in December: 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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