Average Air Temperatures in Phoenix During December: A Comprehensive Weather Guide

Phoenix, Arizona, often conjures images of blistering summer heat and shimmering asphalt. However, as the calendar turns to December, the “Valley of the Sun” undergoes a dramatic transformation. For travelers, seasonal residents (lovingly known as snowbirds), and locals alike, understanding the nuances of the Phoenix winter climate is essential for planning outdoor activities, wardrobe choices, and holiday festivities.

This guide provides an in-depth analysis of average air temperatures in Phoenix during December, exploring the meteorological factors at play, what to pack, and how to make the most of the desert’s most pleasant season.

The General Climate Profile of Phoenix in December

In December, Phoenix transitions into its version of winter. While much of the Northern Hemisphere grapples with snow and sub-zero temperatures, Phoenix enjoys a Mediterranean-like coolness combined with the dry clarity of the Sonoran Desert.

Average High and Low Temperatures

The thermal range in December is one of the most comfortable of the year, but it is characterized by significant diurnal temperature swings—a common trait of desert environments.

• Average Daily High: 66°F (19°C)
• Average Daily Low: 45°F (7°C)
• Record High: 80°F (27°C)
• Record Low: 22°F (-6°C)

During the day, the sun remains strong, often making it feel warmer than the thermometer suggests. However, as soon as the sun dips below the White Tank or Superstition Mountains, the lack of humidity allows heat to escape rapidly into the atmosphere, leading to crisp, chilly evenings.

Weekly Temperature Breakdown

Weather patterns can shift slightly as the month progresses, moving from the lingering warmth of late autumn toward the peak of the winter solstice.

Early December (December 1–10)

At the start of the month, afternoon highs frequently reach the high 60s or low 70s. It is not uncommon to see residents wearing t-shirts during lunch hours. The air is typically very dry, and the skies are famously blue.

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Mid-December (December 11–20)

As we approach the solstice, the sun’s angle is at its lowest. Average highs may dip slightly toward 64°F or 65°F. This period often sees the arrival of occasional cold fronts from the Pacific Northwest, which can bring brief periods of cloud cover.

Late December (December 21–31)

The final week of the year is statistically the coolest. Morning frosts are rare but possible in the outlying desert suburbs like Buckeye or Queen Creek. Highs hover around 63°F, while nighttime lows can occasionally flirt with the high 30s during particularly cold snaps.

Precipitation and Humidity: The “Dry” Factor

Phoenix averages only about 0.74 inches of rain in December. While this makes it one of the wetter months relative to the bone-dry May or June, it is still remarkably arid by global standards.

December rain in Phoenix usually comes in the form of “winter rains”—long, gentle drizzles resulting from Pacific storm tracks, rather than the violent, localized thunderstorms seen during the summer Monsoon. These rains are vital for the desert ecosystem, sparking the growth of wildflowers that will bloom in the coming spring.

Humidity levels remain low, typically fluctuating between 30% and 50%. This low humidity is a double-edged sword: it prevents the “bone-chilling” damp cold found in the Midwest, but it also means your skin and hydration levels will need extra attention.

Sunlight and Daylight Hours

One of the primary reasons people flock to Phoenix in December is the abundance of Vitamin D.

• Sunshine Probability: Phoenix enjoys sunshine approximately 77% of the time in December.
• Daylight Duration: You can expect about 10 hours of daylight.
• Sunrise: Usually occurs around 7:20 AM.
• Sunset: Usually occurs around 5:20 PM.

The early sunset is a crucial factor for hikers and golfers. Once the sun disappears, the temperature can drop by 10 to 15 degrees within a single hour.

Microclimates: Urban Heat Island vs. The Desert Fringe

When looking at “average temperatures,” it is important to note where those temperatures are recorded. Official readings are taken at Phoenix Sky Harbor International Airport. Due to the Urban Heat Island (UHI) effect, the concrete-heavy downtown core stays significantly warmer at night than the surrounding desert.

If you are staying in a resort in Scottsdale, Cave Creek, or the foothills of South Mountain, expect nighttime temperatures to be 5°F to 8°F cooler than the official airport reading. Conversely, daytime highs remain fairly consistent across the valley.

What to Wear: The “Layering” Strategy

Packing for Phoenix in December can be tricky because you are essentially preparing for two different climates in one day.

1. The Base Layer: Light cotton t-shirts or long-sleeve shirts are perfect for midday.
2. The Mid Layer: A light sweater, flannel, or fleece is essential for mornings and shaded areas.
3. The Outer Layer: A medium-weight jacket or a stylish denim/leather jacket is necessary for evening outdoor dining or holiday light tours.
4. Footwear: Comfortable walking shoes or sneakers are standard. Unless you are heading to a formal event, Phoenix is an incredibly casual city.

Expert Tip: Don’t forget your sunglasses. The winter sun sits lower in the sky, creating a significant glare during morning and evening commutes.

Top Activities to Enjoy in Phoenix December Weather

The mild temperatures make December the peak season for outdoor recreation.

1. Hiking Camelback Mountain or Piestewa Peak

In the summer, these trails are dangerous due to heat exhaustion. In December, they are perfect. Start your hike around 10:00 AM when the air has warmed up, and you’ll enjoy panoramic views of the valley under a mild sun.

2. Golfing

Phoenix and Scottsdale are world-renowned golf destinations. December offers “chamber of commerce” weather for the links. Be aware that “overseeded” grass (the lush green winter rye) can be damp with dew in the early morning, so afternoon tee times are often preferred.

3. Desert Botanical Garden: Las Noches de las Luminarias

This is a quintessential Phoenix holiday tradition. The garden paths are lit with thousands of hand-placed luminaria bags. Because this is an outdoor evening event, you will definitely want a heavy sweater or coat, as desert temperatures drop quickly after dark.

Comparing Phoenix to Other Winter Destinations

To put Phoenix’s December weather into perspective, consider how it stacks up against other popular cities:

Phoenix offers a rare middle ground—cool enough to feel like the holidays, but warm enough to avoid the logistical nightmares of ice and snow.

Potential Weather Extremes

While the averages are pleasant, nature occasionally throws a curveball.

• Frost Warnings: Every few years, an Arctic blast reaches southern Arizona. If temperatures are predicted to drop below 32°F, locals must cover sensitive citrus trees and succulents with burlap or “frost cloth.”
• Dust Storms: While more common in the summer, strong winter fronts can occasionally trigger localized dust events, though these are rare in December.

Health and Wellness Tips for the Desert Winter

Even though it isn’t “hot,” the desert environment still requires specific care:

• Hydration: The dry air wicks moisture from your body without you noticing. Drink plenty of water even if you don’t feel thirsty.
• Sun Protection: You can still get a sunburn in 65-degree weather. The UV index in Phoenix remains moderate even in winter.
• Skin Care: The drop in humidity can lead to dry skin and chapped lips. Pack a heavy-duty moisturizer and lip balm.

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Conclusion

December is arguably the best month to experience Phoenix. The air is crisp, the sky is a vivid cerulean, and the temperatures are ideal for nearly any outdoor pursuit. Whether you are escaping a northern blizzard or just looking for a festive desert getaway, the average highs of 66°F and lows of 45°F provide a refreshing backdrop for the holiday season.

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