December weather forecastHayward, CA
December
Weather in December
December in Hayward is synonymous with cool weather, increased rainfall, and heightened humidity. With the pressure peaking this month, temperatures hit their annual lowest, and daylight hours are at their scanty best. The increased rainfall furthers the cloudy conditions, reducing visibility. Wind pressure in December clocks in an average of 30.11" (765mm), the highest for the year. Despite the drop in wind speeds, the increased rainfall and cloudy conditions forecast a cold and wet end to the year.Temperature
December is the coldest month, exhibiting average temperatures of 55.9°F (13.3°C) at the peak and 43.7°F (6.5°C) at the base.Humidity
In Hayward, 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, 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 9h and 36min of daylight.On the first day of the month, sunrise is at 7:05 am and sunset at 4:49 pm. On the last day of December, sunrise is at 7:23 am and sunset at 5:00 pm PST.
Sunshine
The month with the least sunshine is December, with an average of 5.9h of sunshine.UV index
January, February, November and December, with an average maximum UV index of 3, are months with the lowest UV index. A UV Index value of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for the average person.Note: In December, the UV index of 3 transforms into the following advice:
Ensure safety - Recommendations to avert sunburn are presented. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. 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.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
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).
Average pressure in December
Hayward, CA
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).
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).
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%).
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").
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).
Average daylight in December /
Average sunshine in December
Hayward, CA
- Average daylight in December: 9h and 36min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in December: 5h and 54min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).
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).
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).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in December
Hayward, CA
- Average cloud cover in December: 34
The 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).
Average visibility in December
Hayward, CA
- Average visibility in December: 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).
