December weather forecast
Riverside, CA

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The neon-lit buildings of Riverside, California, and a silhouette of the high mountain in the back
The neon-lit buildings of Riverside, California, and a silhouette of the high mountain in the back

Weather in December

As Riverside revels in the holiday season the weather turns chillier with December marking the onset of winter in the city. Rainfall hits a significant rise, accumulating 1.61" (41mm) through the month. Sporadic cloud cover blankets the cityscape, setting December’s distinctive ambience. Despite the characteristic chill, the city receives an average of nearly 7 hours of daily sunshine. All in all, December weather marks a characteristic close to the year with its cooler environment and soothing rainfall.

Temperature

December, noted for its average high-temperature of 63.3°F (17.4°C) and an average low-temperature of 45.9°F (7.7°C), is considered the coldest month in Riverside.

Humidity

In Riverside, the average relative humidity in December is 51%.

Rainfall

The months with the most rainfall in Riverside, California, are February and December, with an average 1.61" (41mm) of precipitation.

Snowfall

January, March through December are months without snowfall.

Daylight

With an average of 9h and 54min of daylight, December has the shortest days of the year in Riverside.
On the first day of the month, sunrise is at 6:37 am and sunset at 4:40 pm. On the last day of December, sunrise is at 6:54 am and sunset at 4:51 pm PST.

Sunshine

February and December, with an average of 6.8h of sunshine, are months with the least sunshine.

UV index

The month with the lowest UV index in Riverside is December, with an average maximum UV index of 3. A UV Index reading of 3 to 5 represents a moderate threat to health from unprotected exposure to Sun's UV rays for average individuals.
Note: The daily high UV index of 3 during December translates into the following recommendations:
Safety measures are advised. Light-skinned individuals may experience burns in under half an hour. For health reasons, it's advisable to reduce direct sun exposure during peak hours around midday. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days.

Frequently asked questions

What is the coldest time of year in Riverside?

December is the coldest month of the year in Riverside, California, registering average temperatures as high as 63.3°F (17.4°C) and as low as 45.9°F (7.7°C).

What are the temperatures in Riverside in December?

The high-temperature, in December, in Riverside, records 63.3°F (17.4°C), while the low-temperature is 45.9°F (7.7°C). The average heat index (a.k.a. 'real feel', 'apparent temperature'), which combines relative humidity and air temperature, in September is appraised at 89.6°F (32°C).

What is the average humidity in December in Riverside?

The average relative humidity in December in Riverside is 51%.

What is the rainiest month in Riverside?

The months with the most rainfall are February and December, with an average 1.61" (41mm) of precipitation.

How much does it rain in Riverside in December?

In Riverside, during December, the rain falls for 5.8 days and regularly aggregates up to 1.61" (41mm) of precipitation.

When it does not snow in Riverside?

January, March through December are months without snowfall in Riverside.

What is the month with the shortest days in Riverside?

December has the shortest days of the year in Riverside, with an average of 9h and 54min of daylight.

What is the average length of the day in December in Riverside?

In December, the average day length in Riverside is 9h and 56min.

When is the sunrise / sunset in December in Riverside?

In December, on the first day of the month, sunrise is at 6:37 am and sunset at 4:40 pm. On the last day of the month, sunrise is at 6:54 am and sunset at 4:51 pm PST.

What are the months with the least sunshine in Riverside?

February and December, with an average of 6.8h of sunshine, are months with the least sunshine in Riverside, California.

How many hours of sunshine does Riverside have in December?

In Riverside, California, the average sunshine duration in December is 6.8h.

When is the lowest UV index in Riverside?

December is the month with the lowest UV index, with an average maximum UV index of 3.

How high is the UV index in December in Riverside?

In Riverside, the average daily maximum UV index in December is 3. A UV Index of 3 to 5 symbolizes a moderate health threat from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Riverside, CA

Average temperature in December - Riverside, CA
  • Average high temperature in December: 63.3°F

The warmest month (with the highest average high temperature) is August (91.2°F).
The month with the lowest average high temperature is December (63.3°F).

  • Average low temperature in December: 45.9°F

The month with the highest average low temperature is August (66.4°F).
The coldest month (with the lowest average low temperature) is December (45.9°F).

Average pressure in December
Riverside, CA

Average pressure in December - Riverside, CA
  • Average pressure in December: 30.07"Hg

The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).

Average wind speed in December
Riverside, CA

Average wind speed in December - Riverside, CA
  • Average wind speed in December: 5mph

The windiest month (with the highest average wind speed) is May (5.6mph).
The calmest month (with the lowest average wind speed) is September (4.4mph).

Average humidity in December
Riverside, CA

Average humidity in December - Riverside, CA
  • Average humidity in December: 51%

The month with the highest relative humidity is May (56%).
The month with the lowest relative humidity is August (43%).

Average rainfall in December
Riverside, CA

Average rainfall in December - Riverside, CA
  • Average rainfall in December: 1.61"

The wettest months (with the highest rainfall) are February and December (1.61").
The driest month (with the least rainfall) is June (0.04").

Average rainfall days in December
Riverside, CA

Average rainfall days in December - Riverside, CA
  • Average rainfall days in December: 5.8 days

The month with the highest number of rainy days is March (7.7 days).
The month with the least rainy days is June (1.1 days).

Average snowfall days in December
Riverside, CA

Average snowfall days in December - Riverside, CA
  • Average snowfall days in December: 0 days

The month with the highest number of snowfall days is February (0.1 days).
The months with the least snowfall days are January, March, April, May, June, July, August, September, October, November and December (0 days).

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

Average daylight in December / Average sunshine in December - Riverside, CA
  • Average daylight in December: 9h and 5min

The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).

  • Average sunshine in December: 6h and 5min

The months with the most sunshine are July and August (Average sunshine: 12h and 6min).
The months with the least sunshine are February and December (Average sunshine: 6h and 48min).

Average sunshine days in December
Riverside, CA

Average sunshine days in December - Riverside, CA
  • Average sunshine days in December: 23.8 days

The month with the most sunshine days is June (27.9 days).
The month with the least sunshine days is February (21.6 days).

Average UV index in December
Riverside, CA

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

The months with the highest UV index are July and August (UV index 7).
The month with the lowest UV index is December (UV index 3).

Average cloud cover in December
Riverside, CA

Average cloud cover in December - Riverside, CA
  • Average cloud cover in December: 22

The months with the most cloud cover are February and March (Cloud cover 23).
The month with the least cloud cover is August (Cloud cover 5).

Average visibility in December
Riverside, CA

Average visibility in December - Riverside, 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).

Riverside, California, USA

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