December is one of the cooler months of the year in Phoenix, with average highs near 18.8°C and lows around 5.3°C (mean 12.1°C). It is about average for rainfall, averaging 34 mm of rainfall and 46% relative humidity across the period.
December is one of the cooler months of the year in Phoenix. Across 45 years of records, the warmest December in Phoenix was 2025 — when the month averaged 16.5°C — while the coldest were 1987 and 2007 at 9.5°C. Typical December days reach 18.8°C with nights near 5.3°C. The long-term trend is warming, about 0.6°C per decade.
December is about average for rainfall in Phoenix, averaging 34 mm of rainfall. The wettest December on record was 1984 with 112 mm, while the driest was 2024 at 0 mm.
Relative humidity in Phoenix during December averages 46%. The most humid December was 1984 at 66%, and the least humid was 2017 at 25%.
December receives about 3.1 kWh/m²/day of solar energy in Phoenix. The sunniest December was 1989 at 3.5 kWh/m²/day, and the cloudiest was 1984 at 2.7.
Average wind speed in Phoenix during December is 1.9 m/s. The windiest Decembers were 1982, 1988 and 1990 at 2.2 m/s, while the calmest were 2014 and 2022 at 1.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 11.5°C | 11.4°C | 11.5°C | 12.4°C | 14.3°C | +2.8°C |
| Avg High | 18.2°C | 18.3°C | 18.4°C | 18.9°C | 21.1°C | +2.9°C |
| Avg Low | 4.8°C | 4.6°C | 4.6°C | 5.9°C | 7.5°C | +2.7°C |
| Avg Rain | 40 mm | 37 mm | 27 mm | 35 mm | 30 mm | -10 mm |
December temperatures in Phoenix have risen by about 2.8°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -8°C (1990) to a record high of 29.6°C (2021).
Rainfall in December is about average for rainfall, averaging 34 mm, with a wettest year of 112 mm.
A quieter season to visit Phoenix
If your dates are flexible, the more temperate months of April and October tend to be the most comfortable for visiting Phoenix. That said, December — with days averaging 18.8°C and nights around 5.3°C (mean 12.1°C) and moderate rainfall (34 mm) — can still be rewarding for travellers who don't mind the cooler conditions, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 🔥 | 23.6°C | 16.5°C | 9.4°C | 27.8°C | 4.2°C | 3 mm | 44% | 1.8 m/s | — |
| 2024 | 23.7°C | 16.2°C | 8.7°C | 28.5°C | 3.8°C | 0 mm | 26% | 1.6 m/s | 3.3 |
| 2023 | 21.2°C | 14.3°C | 7.5°C | 27.8°C | 0.9°C | 30 mm | 39% | 1.7 m/s | 3.1 |
| 2022 | 17.9°C | 12.1°C | 6.2°C | 24.3°C | -0.3°C | 57 mm | 56% | 1.5 m/s | 2.9 |
| 2021 | 20.1°C | 14.0°C | 7.9°C | 29.6°C | 0.8°C | 78 mm | 48% | 1.6 m/s | 2.9 |
| 2020 | 19.8°C | 12.4°C | 5.1°C | 26.4°C | 0.6°C | 11 mm | 31% | 2 m/s | 3.3 |
| 2019 | 17.6°C | 11.8°C | 6.0°C | 22.9°C | -2.2°C | 50 mm | 57% | 1.8 m/s | 2.8 |
| 2018 | 18.6°C | 12.1°C | 5.7°C | 24.1°C | -1.2°C | 16 mm | 46% | 1.7 m/s | 3 |
| 2017 | 22.4°C | 15.2°C | 8.0°C | 27.7°C | 0.3°C | 4 mm | 25% | 1.9 m/s | 3.2 |
| 2016 | 19.7°C | 13.5°C | 7.4°C | 24.9°C | 0.4°C | 56 mm | 52% | 1.8 m/s | 2.9 |
| 2015 | 17.5°C | 10.7°C | 4.0°C | 26.0°C | -1.1°C | 19 mm | 44% | 1.7 m/s | 3.2 |
| 2014 | 18.6°C | 12.8°C | 7.0°C | 26.2°C | -0.4°C | 42 mm | 52% | 1.5 m/s | 2.8 |
| 2013 | 18.6°C | 11.4°C | 4.2°C | 26.9°C | -2.1°C | 17 mm | 46% | 2 m/s | 3.3 |
| 2012 | 18.4°C | 12.1°C | 5.9°C | 27.5°C | -0.9°C | 45 mm | 44% | 1.7 m/s | 3.2 |
| 2011 | 16.8°C | 10.2°C | 3.6°C | 25.3°C | -2.4°C | 49 mm | 52% | 1.9 m/s | 3 |
| 2010 | 20.9°C | 14.2°C | 7.6°C | 28.4°C | -4.0°C | 52 mm | 44% | 1.9 m/s | 2.9 |
| 2009 | 16.6°C | 10.2°C | 3.9°C | 22.7°C | -1.5°C | 30 mm | 45% | 1.9 m/s | 3 |
| 2008 | 17.7°C | 11.4°C | 5.0°C | 25.5°C | -2.3°C | 67 mm | 53% | 1.9 m/s | 2.9 |
| 2007 | 16.2°C | 9.5°C | 2.9°C | 25.2°C | -2.2°C | 59 mm | 52% | 1.8 m/s | 3.3 |
| 2006 | 18.7°C | 11.4°C | 4.2°C | 26.0°C | -1.7°C | 7 mm | 38% | 1.9 m/s | 3.2 |
| 2005 | 20.9°C | 13.5°C | 6.1°C | 26.5°C | 0.4°C | 0 mm | 26% | 1.7 m/s | 3.1 |
| 2004 | 18.8°C | 11.8°C | 4.9°C | 26.8°C | -1.5°C | 54 mm | 49% | 1.9 m/s | 3.1 |
| 2003 | 19.3°C | 12.3°C | 5.2°C | 26.4°C | -3.3°C | 11 mm | 40% | 2 m/s | 3.3 |
| 2002 | 17.8°C | 11.2°C | 4.7°C | 22.4°C | 0.0°C | 13 mm | 50% | 1.6 m/s | 3.2 |
| 2001 | 17.7°C | 10.5°C | 3.3°C | 23.6°C | -1.7°C | 25 mm | 45% | 1.8 m/s | 3.1 |
| 2000 | 20.4°C | 13.0°C | 5.6°C | 24.7°C | 1.3°C | 2 mm | 43% | 1.8 m/s | 3.3 |
| 1999 | 20.1°C | 12.3°C | 4.6°C | 24.8°C | -0.2°C | 0 mm | 26% | 2.1 m/s | 3.4 |
| 1998 | 18.7°C | 11.4°C | 4.2°C | 26.7°C | -3.0°C | 12 mm | 48% | 2 m/s | 3.2 |
| 1997 | 16.7°C | 10.1°C | 3.5°C | 22.3°C | -2.7°C | 46 mm | 53% | 2 m/s | 3.2 |
| 1996 | 20.1°C | 12.7°C | 5.3°C | 27.0°C | -2.6°C | 2 mm | 37% | 1.9 m/s | 3.2 |
| 1995 | 20.3°C | 13.2°C | 6.1°C | 26.0°C | 1.7°C | 2 mm | 38% | 1.8 m/s | 3.2 |
| 1994 | 17.8°C | 11.6°C | 5.5°C | 24.4°C | -0.9°C | 83 mm | 56% | 2 m/s | 2.9 |
| 1993 | 18.7°C | 11.3°C | 3.8°C | 24.6°C | -1.8°C | 3 mm | 45% | 2 m/s | 3.4 |
| 1992 | 16.2°C | 10.0°C | 3.8°C | 21.3°C | -1.6°C | 109 mm | 60% | 1.9 m/s | 2.9 |
| 1991 | 17.8°C | 12.0°C | 6.1°C | 23.2°C | -2.7°C | 63 mm | 61% | 2.1 m/s | 3.1 |
| 1990 | 16.6°C | 9.7°C | 2.8°C | 25.2°C | -8.0°C | 47 mm | 49% | 2.2 m/s | 3.2 |
| 1989 | 20.0°C | 12.5°C | 4.9°C | 24.9°C | -0.8°C | 14 mm | 33% | 2 m/s | 3.5 |
| 1988 | 17.7°C | 10.9°C | 4.1°C | 24.6°C | -3.7°C | 7 mm | 44% | 2.2 m/s | 3.2 |
| 1987 ❄️ | 15.8°C | 9.5°C | 3.1°C | 24.9°C | -3.7°C | 41 mm | 52% | 1.8 m/s | 3.1 |
| 1986 | 18.2°C | 11.6°C | 5.0°C | 24.3°C | -0.7°C | 47 mm | 53% | 1.9 m/s | 3 |
| 1985 | 19.4°C | 12.1°C | 4.7°C | 24.3°C | -2.7°C | 24 mm | 50% | 2 m/s | 3.4 |
| 1984 🌧️ | 16.9°C | 11.3°C | 5.7°C | 24.8°C | 0.3°C | 112 mm | 66% | 2 m/s | 2.7 |
| 1983 | 18.1°C | 11.7°C | 5.2°C | 23.4°C | -0.2°C | 48 mm | 60% | 1.9 m/s | — |
| 1982 | 16.7°C | 10.3°C | 4.0°C | 23.5°C | -0.4°C | 57 mm | 59% | 2.2 m/s | — |
| 1981 | 21.1°C | 13.8°C | 6.4°C | 27.8°C | 0.0°C | 6 mm | 44% | 1.8 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 18.8°C with lows near 5.3°C (mean 12.1°C), based on 45 years of NASA POWER data.
December averages 34 mm of rainfall in Phoenix, about average for rainfall. The wettest on record was 112 mm in 1984.
The hottest December reached 29.6°C in 2021. The coldest dipped to -8°C in 1990.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 2.8°C. Daytime highs moved from 18.4°C to 21.3°C and overnight lows from 5.2°C to 7.9°C over the same span.
December is one of the cooler months of the year in Phoenix and about average for rainfall, so plan for around 18.8°C daytime highs and 5.3°C at night.
Not quite — December is the 2nd coolest month in Phoenix, averaging 12.1°C.
For December in Phoenix, pack warm layers and a jacket for chilly mornings, with typical highs of 18.8°C and lows of 5.3°C.
Relative humidity in December averages 46% — relatively dry.
Average wind speed in December is 1.9 m/s. The windiest December on record averaged 2.2 m/s (1982).
The wettest December on record was 1984 with 112 mm. On average, December sees 34 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Phoenix behaves each December, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for December specifically, along with year-by-year records and how the month has changed over the decades.
