December Weather in Flagstaff, United States

Last updated: February 24, 2025

In Flagstaff, United States, December ushers in a striking blend of winter conditions, with maximum temperatures reaching 16°C (62°F) and plunging to a chilly minimum of -20°C (-4°F). The average temperature hovers around 1°C (33°F), creating a brisk atmosphere ideal for seasonal activities. With precipitation amounting to 36 mm (1.4 in) over 6 days, the month is characterized by a moist climate, contributing to a relative humidity of 82%. This combination of cold temperatures and periodic precipitation showcases the enchanting winter charm of Flagstaff, making it a picturesque destination during the holiday season.

December Temperature in Flagstaff

In December, Flagstaff, United States experiences a notable drop in temperatures as winter firmly takes hold. The month typically sees minimum temperatures plummeting to -20°C (-4°F), presenting a stark contrast to the milder conditions of the preceding months. The average temperature hovers around 1°C (33°F), allowing for chilly days that occasionally peak at a maximum of 16°C (62°F). This sharp decline marks a significant seasonal transition, as December's temperatures dip even lower than in November, indicating a clear tendency towards colder weather as the year concludes. The crisp air and occasional snowfall transform Flagstaff into a picturesque winter landscape, making it a prime destination for winter enthusiasts and a serene retreat for those seeking the charm of a snowy season.

December Weather in Flagstaff: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Flagstaff, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec323339495668706963514233
Data source: Temperature data for Flagstaff generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Flagstaff

In December, Flagstaff experiences a notable drop in precipitation compared to the summer months, receiving 36 mm (1.4 in) over 6 days. This marks a continuation of the trend observed throughout the fall, where the precipitation levels gradually decline from the higher summer figures, with July peaking at a substantial 148 mm (5.8 in). While December's precipitation is moderate, it sets the stage for a drier winter season ahead. The month’s rainfall is significantly lower than the winter months of January and February, which see an uptick in precipitation, averaging 47 mm (1.8 in) and 50 mm (2.0 in) respectively. As the year closes, the transition from the lush summer to the crisp, cooler months is evident, highlighting Flagstaff’s dynamic climate.

December Precipitation Trends in Flagstaff

The chart displays monthly precipitation patterns in Flagstaff, with values for each month alongside December's data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December's conditions compare to those of other months.
JanFebMarAprMayJunJulAugSepOctNovDec4750612232111486949343037
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

December Humidity in Flagstaff

In Flagstaff, December embodies a return to higher humidity levels, with an average of 82%, reflecting a trend of rising moisture as the year concludes. Following a brief dip during the warmer months, where humidity plummeted to a mere 33% in July, the latter half of the year witnesses a gradual increase, peaking in winter. Notably, as the seasons shift, December's humidity closely mirrors that of January and February, both of which remain above 80%. This consistent trend emphasizes Flagstaff's cool and crisp winters, shaping not just the landscape but also the experience of its residents and visitors alike.

December Average Humidity in Flagstaff

This chart illustrates the average monthly humidity levels in Flagstaff, with December's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how December's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec80%83%72%63%46%35%33%41%59%70%79%82%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Flagstaff

In December, Flagstaff experiences a moderate UV Index of 4, making it a time when sun exposure is relatively safe, with a burn time of approximately 30 minutes. This marks a notable decrease from the extreme levels seen earlier in the year, particularly during the summer months, where indices soared to 13, necessitating careful sun safety practices with burn times as short as 10 minutes. As the year transitions to winter, residents and visitors can enjoy the outdoors with less concern for UV-related harm, but should still be mindful of occasional sun exposure, especially in clear conditions. For detailed information on the UV levels throughout the year, check out the Flagstaff UV Index.

Maximum UV Index Levels in Flagstaff for December

The chart shows the monthly maximum UV Index (UVI) for Flagstaff in December, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec589111213131211864
Data source: Flagstaff December UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

December Sunshine in Flagstaff

As December unfolds in Flagstaff, the city basks in a modest 232 hours of sunshine, a number that reflects a noticeable decline from the sunniest months of late spring and early summer. While the year begins with a sparse 188 hours of sunlight in January, the trend quickly shifts upward, peaking in May with an impressive 374 hours. As the seasons transition, the sunlit hours gradually decrease, showcasing the influence of winter's embrace. Interestingly, December's sunshine shines brighter than the earlier winter months but still trails significantly behind the sun-soaked days of mid-year. This pattern highlights the delicate balance of seasons, where the chill of winter is met with the warmth of the sun, offering a unique charm to Flagstaff during this festive month.

Monthly Sunshine Duration in Flagstaff: December Highlighted

The December sunshine duration represents the total number of hours Flagstaff experiences direct sunlight during the month of December, excluding cloudy or obstructed periods. This chart compares the sunshine duration of December with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec188h242h301h331h374h375h361h348h316h294h258h232h
Data source: Flagstaff December Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Flagstaff During December

In Flagstaff, December presents a notable shift in sunny weather, with only a 48% chance of sunshine—the lowest of the year. This decline contrasts sharply with the preceding months, where the likelihood of clear skies remains consistently higher, particularly in November at 75%. As we transition from the vibrant fall months into winter, the trend indicates that while Flagstaff generally enjoys a good amount of sun, the approach of December brings a mix of clouds and cooler temperatures, making it a time to prepare for the coziness of winter rather than outdoor adventures. Despite the winter chill, those lucky enough to catch a sunny day in December can relish the beautiful contrast of snow-covered landscapes and blue skies.

Percentage of Sunny Days in December in Flagstaff

The chart illustrates the percentage of sunny days in Flagstaff throughout the year, with December highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Flagstaff experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec51%71%64%73%77%60%31%58%67%67%75%48%
Data source: Flagstaff December chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Flagstaff in December

In December, Flagstaff experiences the shortest daylight duration of the year, with only 9 hours of sunlight. This decrease begins in November when daylight reduces to 10 hours and continues its downward trend throughout the winter months. Following a gradual increase in light from January to May, where daylight peaks at an impressive 14 hours in both June and July, the cycle then descends once more, leading back into shorter days as autumn sets in. The shift from 14 hours in mid-summer to just 9 hours in December highlights the distinct seasonal changes that define life in this mountainous region. As we welcome the winter solstice, residents may feel the embrace of longer nights, but the promise of lengthening days is just around the corner.

Average Daylight Hours in Flagstaff for December

The chart illustrates the variation in daylight duration in Flagstaff throughout the year, with December highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec10h 4m10h 55m11h 59m13h 6m14h 1m14h 28m14h 13m13h 24m12h 20m11h 14m10h 17m9h 48m
Data source: Flagstaff daylight hours, calculated by summing the hours between sunrise and sunset for each day.

December Winds in Flagstaff

As December descends upon Flagstaff, the winds begin to pick up, with an average speed of 3.2 m/s (7 mph) that adds a brisk chill to the already frosty air. This marks a notable increase from the quieter summer months, where July experienced the lowest gusts at just 2.0 m/s (4 mph). As the year progresses, the wind speed gradually rises, peaking in April and tapering off again toward the end of the year. While winter brings a chill, the December winds provide a spirited reminder of nature’s dynamic essence, making it a month of refreshing breezes that signal the beauty of the season ahead.

Average December Wind Speed in Flagstaff

The chart displays monthly wind speed patterns in Flagstaff, with values for each month shown alongside December's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how December's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec2.43.03.33.63.32.92.02.42.12.92.33.2 m/s
Data source: Flagstaff December wind data, generated using information from the Copernicus Climate Change Service.

How December Weather in Flagstaff Compares to Other Months

The weather in Flagstaff changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of December's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Flagstaff and find detailed weather information for every month.

In December, temperatures in Flagstaff exhibit a range from a chilly minimum of -20°C (-4°F) to a more moderate maximum of 16°C (62°F), with an average around 1°C (33°F). The month sees about 36 mm (1.4 in) of precipitation over roughly 6 days, while humidity remains high at 82%. In contrast, January experiences slightly milder temperatures, with a minimum of -18°C (0°F) and a maximum of 14°C (58°F), averaging around 0°C (32°F). Precipitation increases to 47 mm (1.8 in) over 7 days, with humidity slightly lower at 80%. For more detailed weather patterns, check out Flagstaff weather in January.

In comparing the weather between December and February, both months exhibit similar average temperatures, with December showing a minimum of -20°C (-4°F) and February slightly milder at -19°C (-2°F). The average temperatures in both months hover around 1°C (33°F), with February slightly warmer with an average of 1°C (34°F) and a max temperature of 17°C (63°F), while December peaks at 16°C (62°F). Precipitation is more pronounced in February, reaching 50 mm (2.0 in) over 7 days compared to December's 36 mm (1.4 in) over 6 days. Humidity levels are also comparable, with December at 82% and February slightly higher at 83%. For more detailed insights, you can check Flagstaff weather in February.

In December, the weather is typically colder, with temperatures ranging from a minimum of -20°C (-4°F) to a maximum of 16°C (62°F), and an average of around 1°C (33°F). The month sees about 36 mm (1.4 in) of precipitation spread over 6 days, accompanied by relatively high humidity at 82%. In contrast, March experiences milder temperatures, with a minimum of -14°C (8°F) and a maximum of 20°C (69°F), leading to an average of 4°C (39°F). Additionally, March has higher precipitation at 61 mm (2.4 in) over 9 days and a lower humidity level of 72%. For more details, you can check Flagstaff weather in March.

December weather is characterized by significantly colder temperatures, with average highs reaching only 1°C (33°F) and lows plunging to -20°C (-4°F). The month sees an average of 36 mm (1.4 in) of precipitation over about six days, while humidity levels remain high at 82%. In contrast, April offers a much milder climate, with average temperatures rising to 9°C (49°F) and maximums hitting 26°C (79°F). Precipitation in April decreases to 22 mm (0.9 in) over approximately four days, and humidity also falls to a more comfortable 63%. For more detailed information, check out Flagstaff weather in April.

In December, temperatures can plummet, with a minimum of -20°C (-4°F) and an average hovering around 1°C (33°F), while the maximum reaches up to 16°C (62°F). The month experiences around 36 mm (1.4 in) of precipitation over six days, coupled with a high humidity level of 82%. In contrast, May presents a much milder climate, with temperatures starting at a minimum of -3°C (27°F) and averaging 13°C (57°F), peaking at a warm 30°C (86°F). Precipitation slightly decreases to 32 mm (1.3 in) over the same six days, but humidity drops significantly to 46%. For a closer look at the pleasant conditions, check out Flagstaff weather in May.

December and June present striking contrasts in weather. In December, temperatures can drop as low as -20°C (-4°F), with an average of around 1°C (33°F) and highs reaching 16°C (62°F). This month is characterized by higher humidity at 82% and occasional precipitation over six days, totaling 36 mm (1.4 in). In contrast, June boasts much milder conditions, with minimum temperatures of 3°C (37°F) and an average of 20°C (69°F), peaking at a sweltering 35°C (95°F). The summer month is notably drier, experiencing just 11 mm (0.4 in) of precipitation over two days and lower humidity at 35%. For more specifics on the weather during this month, check out Flagstaff weather in June.

In December, the weather contrasts sharply with July, showcasing a much colder climate with average temperatures hovering around 1°C (33°F) and minimum lows plummeting to -20°C (-4°F). The month experiences relatively low precipitation at 36 mm (1.4 in) over six days, coupled with high humidity levels at 82%. In contrast, July presents a vibrant and warm atmosphere, where temperatures average 21°C (70°F) and can soar to a maximum of 35°C (95°F). Precipitation in July is significantly higher, reaching 148 mm (5.8 in) over 16 days, yet the humidity drops to a more comfortable 33%. For a deeper look into the warm conditions during July, check out Flagstaff weather in July.

December weather is characterized by much colder temperatures, with averages hovering around 1°C (33°F) and nighttime lows plunging to -20°C (-4°F). In contrast, August offers a warm reprieve, with average temperatures reaching 20°C (69°F) and highs soaring up to 33°C (92°F). Additionally, December experiences more humidity at 82%, while August has a significantly lower humidity level of 41%. Precipitation is also more frequent in August, with rainfall occurring on 13 days compared to just 6 days in December. For a closer look at the weather specifics, check out Flagstaff weather in August.

December and September present starkly contrasting weather conditions. In December, temperatures can plummet to a minimum of -20°C (-4°F), with an average of just 1°C (33°F) and a maximum reaching 16°C (62°F). The month tends to be quite humid, with a humidity level of 82% and a total precipitation of 36 mm (1.4 in) over approximately 6 days. In contrast, September enjoys milder weather with a minimum temperature of -1°C (31°F), an average of 17°C (63°F), and a maximum of 33°C (91°F). Although September sees slightly more rainfall, with 49 mm (1.9 in) measured over 7 days, its humidity is significantly lower at 59%. For more detailed insights on weather specifics, check out Flagstaff weather in September.

In comparing the weather between October and December, it's clear that December experiences much colder temperatures. While December has an average of 1°C (33°F) with a minimum of -20°C (-4°F), October is milder, with an average temperature of 11°C (51°F) and a minimum of -8°C (17°F). Precipitation levels are similar, with December receiving 36 mm (1.4 in) over 6 days, and October recording 34 mm (1.4 in) over just 5 days. Additionally, December's humidity is notably higher at 82%, compared to October's 70%. For a closer look at what to expect, you can check out Flagstaff weather in October.

In December, the weather takes a colder turn compared to November, with average temperatures dropping from 6°C (42°F) in November to just 1°C (33°F) in December. While December sees a slightly higher precipitation total of 36 mm (1.4 in) over 6 days, November has a lower precipitation of 30 mm (1.2 in) spread over only 3 days. Additionally, humidity levels are slightly elevated in December at 82%, compared to 79% in November. For a closer look at the conditions in November, you can check out Flagstaff weather in November.

Compare Flagstaff's Climate with Cities Worldwide

Conclusion: What to Expect From December Weather in Flagstaff

As we embrace the chill of December in Flagstaff, we witness a dramatic shift from the milder temperatures experienced in earlier months. The average temperature tumbles, offering a crisp wintry feel that sets the stage for potential snowfalls. With increased humidity and a notable chance of precipitation, this month stands out as a pivotal time for the landscape to transform into a picturesque winter wonderland. While the city sees a decrease in sunshine, the enchanting atmosphere of December invites all to explore the unique seasonal offerings. For a deeper dive into how Flagstaff's weather evolves, visit Flagstaff Climate.