Flagstaff
Arizona, USA
Long-term weather forecast
Long-term weather forecast

December weather forecast and climate
Flagstaff, AZ

A close-up of the brown iconic clock tower in the city of Flagstaff, Arizona, with the street signs of Birch Avenue and San Francisco Street
A close-up of the brown iconic clock tower in the city of Flagstaff, Arizona, with the street signs of Birch Avenue and San Francisco Street
December, the first month of the winter, in Flagstaff, is also a wintry month, with average temperature fluctuating between 16.9°F (-8.4°C) and 42.4°F (5.8°C).

Temperature

The coldest months are January and December, with an average high-temperature of 42.4°F (5.8°C).

Humidity

The average relative humidity in December is 60.6%.

Rainfall

In Flagstaff, during December, the rain falls for 7 days and regularly aggregates up to 1.9" (47.5mm) of precipitation. Throughout the year, in Flagstaff, Arizona, there are 87.7 rainfall days, and 21.9" (555.3mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through May, October through December.

Daylight

With an average of 9.8h of daylight, December has the shortest days of the year.

Sunshine

December has the least sunshine of the year in Flagstaff, with an average of 7.1h of sunshine.

UV index

January and December, with an average maximum UV index of 3, are months with the lowest UV index. A UV Index of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to the UV radiation for the average person.
Note: The daily maximum UV index of 3 in December 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. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.

What is the coldest month in Flagstaff?

The coldest months in Flagstaff are January and December, with an average high-temperature of 42.4°F (5.8°C).

What is the temperature in December in Flagstaff?

In Flagstaff, Arizona, in December, the average high-temperature is 42.4°F (5.8°C), and the average low-temperature is 16.9°F (-8.4°C).

What is the average humidity in December in Flagstaff?

In Flagstaff, Arizona, the average relative humidity in December is 60.6%.

How much does it rain in Flagstaff in December?

In Flagstaff, Arizona, in December, it is raining for 7 days, with typically 1.9" (47.5mm) of accumulated precipitation.

How many days does it snow in December in Flagstaff?

In Flagstaff, Arizona, in December, during 6.5 snowfall days, 16.9" (429.3mm) of snow is typically accumulated.

What is the month with the shortest days in Flagstaff?

With an average of 9.8h of daylight, December has the shortest days of the year in Flagstaff.

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

In December, the average length of the day in Flagstaff is 9.8h.

What is the month with the least sunshine in Flagstaff?

The month with the least sunshine is December, with an average of 7.1h of sunshine.

How long on average sun shines in December in Flagstaff?

The average sunshine in December in Flagstaff, Arizona, is 7.1h.

What is the month with the lowest UV index in Flagstaff?

Months with the lowest UV index in Flagstaff, Arizona, are January and December, with an average maximum UV index of 3.

What is the UV index intensity in December in Flagstaff?

In Flagstaff, Arizona, the average daily maximum UV index in December is 3. A UV Index reading of 3 to 5 represents a moderate vulnerability from unsafe exposure to the Sun's UV rays.
Average temperature in December - Flagstaff, AZ
  • Average high temperature in December: 42.5°F

The warmest month (with the highest average high temperature) is July (81.2°F).
Months with the lowest average high temperature are January and December (42.5°F).

  • Average low temperature in December: 16.8°F

The month with the highest average low temperature is July (50.9°F).
The coldest month (with the lowest average low temperature) is December (16.8°F).

Average humidity in December - Flagstaff, AZ
  • Average humidity in December: 60.6%

The month with the highest relative humidity is January (61.9%).
The month with the lowest relative humidity is June (33.6%).

Average rainfall in December - Flagstaff, AZ
  • Average rainfall in December: 1.9"

The wettest month (with the highest rainfall) is August (3.1").
The driest month (with the lowest rainfall) is June (0.4").

Average rainfall days in December - Flagstaff, AZ
  • Average rainfall days in December: 7 days

The month with the highest number of rainy days is August (14 days).
The month with the lowest number of rainy days is June (2.6 days).

Average snowfall in December - Flagstaff, AZ
  • Average snowfall in December: 16.9"

The month with the highest snowfall is January (23.2").
Months with the lowest snowfall are June, July, August and September (0").

Average snowfall days in December - Flagstaff, AZ
  • Average snowfall days in December: 6.5 days

The month with the highest number of snowfall days is January (7.5 days).
Months with the lowest number of snowfall days are June, July, August and September (0 days).

Average daylight in December / Average sunshine in December - Flagstaff, AZ
  • Average daylight in December: 9.8h

The month with the longest days is June (Average daylight: 14.5h).
The month with shortest days is December (Average daylight: 9.8h).

  • Average sunshine in December: 7.1h

The month with most sunshine is June (Average sunshine: 12.4h).
The month with least sunshine is December (Average sunshine: 7.1h).

Average UV index in December - Flagstaff, AZ
  • Average UV index in December: 3

The month with the highest UV index is July (UV index 12).
Months with the lowest UV index are January and December (UV index 3).