December weather forecast
Portal, AZ

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Weather in December

December marks the arrival of winter in Portal, Arizona. With a considerable drop in temperature from November, it is the coldest month of the year. Although the number of daylight hours is at the lowest, the amount of sunshine doesn't decrease by as steep a margin, allowing for bright winter days. A unique feature of December is a significant occurrence of snowfall at around 0.79" (20mm) after being almost absent for most of the year. As the year ends, the city gears up for winter, with brisk winds and cooler temperatures enveloping the landscape.

Temperature

December, on average, is the coldest month in Portal, registering a high temperature of 54.5°F (12.5°C) and a low of 37.6°F (3.1°C).

Humidity

December is the most humid month in Portal, with an average relative humidity of 51%.

Rainfall

In Portal, in December, during 5.2 rainfall days, 0.55" (14mm) of precipitation is typically accumulated. Throughout the year, there are 73.4 rainfall days, and 7.91" (201mm) of precipitation is accumulated.

Snowfall

January through March, November and December are months with snowfall in Portal. December is the month with the most snowfall. Snow falls for 1.5 days and accumulates 0.79" (20mm) of snow.

Daylight

December has the shortest days of the year in Portal, with an average of 10h and 6min of daylight.
On the first day of December in Portal, sunrise is at 6:59 am and sunset at 5:12 pm. On the last day of the month, sunrise is at 7:16 am and sunset at 5:23 pm MST.

Sunshine

The month with the least sunshine in Portal is December, with an average of 7h of sunshine.

UV index

December is the month with the lowest UV index in Portal, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a minimal health hazard from exposure to the Sun's UV radiation for the average person.
Note: A daily maximum UV index of 2 in December translates into the following instructions:
Those with sensitive skin, infants, and children require constant safeguarding from prolonged sun exposure. Limiting sun exposure during midday hours helps in reducing the harmful effects of UV radiation. For excellent sun protection for the eyes, ears, face, and neck, consider a wide-brim hat. Take heed! The reflection of snow can intensify the Sun's UV radiation nearly double.
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Frequently asked questions

What part of the year is the coldest in Portal?

The coldest period is December, when temperatures fluctuate between an average high of 54.5°F (12.5°C) and a low of 37.6°F (3.1°C).

What are the temperatures in Portal in December?

In December, the average high-temperature and low-temperature in Portal are 54.5°F (12.5°C) and 37.6°F (3.1°C) respectively. The average heat index (a.k.a. 'felt air temperature', 'feels like'), which takes the relative humidity and factors it into the air temperature reading, in September is estimated at 84.2°F (29°C).

What is the most humid month in Portal?

The most humid month in Portal, Arizona, is December, with an average relative humidity of 51%.

What is the average humidity in December in Portal?

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

How many days does it rain in December in Portal?

In Portal, during December, the rain falls for 5.2 days and regularly aggregates up to 0.55" (14mm) of precipitation.

When does it snow the most in Portal?

The month with the most snowfall in Portal, Arizona, is December, when snow falls for 1.5 days and typically aggregates up to 0.79" (20mm) of snow.

How much does it snow in Portal in December?

In Portal, Arizona, during December, snow falls for 1.5 days and regularly aggregates up to 0.79" (20mm) of snow.

What is the month with the shortest days in Portal?

With an average of 10h and 6min of daylight, December has the shortest days of the year in Portal, Arizona.

How many hours of daylight does Portal have in December?

In Portal, the average day length in December is 10h and 6min.

What time are sunrise and sunset in December in Portal?

On the first day of December in Portal, sunrise is at 6:59 am and sunset at 5:12 pm. On the last day of the month, sunrise is at 7:16 am and sunset at 5:23 pm MST.

What is the month with the least sunshine in Portal?

December has the least sunshine of the year, with an average of 7h of sunshine.

How many hours of sunshine does Portal have in December?

In Portal, the average sunshine duration in December is 7h.

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

The month with the lowest UV index in Portal is December, with an average maximum UV index of 2.

What is the UV index reading in December in Portal?

In December, the average daily maximum UV index in Portal, Arizona, is 2. A UV Index estimate of 2, and below, represents a minimal health vulnerability from unprotected exposure to UV radiation.
Today
Tomorrow
Long-term
YearJFMAMJJASONDecember
Nov
December
Jan
Average high temperature
63.9°F 17.7°C
54.5°F 12.5°C
54.9°F 12.7°C
Average low temperature
44.1°F 6.7°C
37.6°F 3.1°C
36.3°F 2.4°C
Average pressure
30.06" 764mmHg
30.07" 764mmHg
30.11" 765mmHg
Average wind speed
8mph 12.9km/h
7.4mph 11.9km/h
7.1mph 11.4km/h
Average max. wind speed
8.9mph 14.3km/h
8.3mph 13.4km/h
7.9mph 12.7km/h
Average wind speed gusts
13mph 20.9km/h
12.1mph 19.5km/h
11.7mph 18.8km/h
Average humidity
43%
51%
47%
Average rainfall
0.71" 18mm
0.55" 14mm
0.31" 8mm
Average rainfall days
3.5
5.2
3.8
Average snowfall
0.04" 1mm
0.79" 20mm
0.24" 6mm
Average snowfall days
0.2
1.5
1.1
Average daylight
10h 3min
10h 1min
10h 2min
Average sunshine
7h 2min
7h 0min
7h 1min
Average sunshine days
25.4
25.1
26.3
Average UV index
3
2
3
Average cloud cover
14%
20%
17%
Average visibility
6mi 9.7km
6mi 9.7km
6mi 9.7km

Average temperature in December
Portal, AZ

Average temperature in December - Portal, AZ
  • Average high temperature in December: 54.5°F

The warmest month (with the highest average high temperature) is June (92.8°F).
The month with the lowest average high temperature is December (54.5°F).

  • Average low temperature in December: 37.6°F

The month with the highest average low temperature is July (73°F).
The coldest month (with the lowest average low temperature) is January (36.3°F).

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Average pressure in December
Portal, AZ

Average pressure in December - Portal, AZ
  • Average pressure in December: 30.07"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).

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Average wind speed in December
Portal, AZ

Average wind speed in December - Portal, AZ
  • Average wind speed in December: 7.4mph

The windiest month (with the highest average wind speed) is April (11.1mph).
The calmest month (with the lowest average wind speed) is January (7.1mph).

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Average humidity in December
Portal, AZ

Average humidity in December - Portal, AZ
  • Average humidity in December: 51%

The month with the highest relative humidity is December (51%).
The month with the lowest relative humidity is May (21%).

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Average rainfall in December
Portal, AZ

Average rainfall in December - Portal, AZ
  • Average rainfall in December: 0.55"

The wettest month (with the highest rainfall) is July (1.81").
The driest month (with the least rainfall) is April (0.12").

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Average rainfall days in December
Portal, AZ

Average rainfall days in December - Portal, AZ
  • Average rainfall days in December: 5.2 days

The month with the highest number of rainy days is July (15 days).
The month with the least rainy days is May (2.1 days).

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Average snowfall in December
Portal, AZ

Average snowfall in December - Portal, AZ
  • Average snowfall in December: 0.79"

The month with the highest snowfall is December (0.79").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in December
Portal, AZ

Average snowfall days in December - Portal, AZ
  • Average snowfall days in December: 1.5 days

The month with the highest number of snowfall days is December (1.5 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).

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Average daylight in December /
Average sunshine in December
Portal, AZ

Average daylight in December / Average sunshine in December - Portal, AZ
  • Average daylight in December: 10h and 1min

The month with the longest days is June (Average daylight: 14h and 12min).
The month with the shortest days is December (Average daylight: 10h and 6min).

  • Average sunshine in December: 7h and 0min

The month with the most sunshine is June (Average sunshine: 11h and 54min).
The month with the least sunshine is December (Average sunshine: 7h and 0min).

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Average sunshine days in December
Portal, AZ

Average sunshine days in December - Portal, AZ
  • Average sunshine days in December: 25.1 days

The month with the most sunshine days is May (28.5 days).
The month with the least sunshine days is July (9.9 days).

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Average UV index in December
Portal, AZ

Average UV index in December - Portal, AZ
  • Average UV index in December: 2

The months with the highest UV index are May, June, July and August (UV index 7).
The month with the lowest UV index is December (UV index 2).

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Average cloud cover in December
Portal, AZ

Average cloud cover in December - Portal, AZ
  • Average cloud cover in December: 20

The months with the most cloud cover are July and December (Cloud cover 20).
The month with the least cloud cover is May (Cloud cover 8).

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Average visibility in December
Portal, AZ

Average visibility in December - Portal, AZ
  • 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).

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Portal, Arizona, USA

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