Phoenix braces for another warm December
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Climate change has raised winter temperatures nationally and in Phoenix over the past half-century, and this month is shaping up to be particularly warm, according to weather outlooks.
Why it matters: Widespread heat across northern Arizona and the Rocky Mountain region affects water supplies tied to annual snowmelt.
The big picture: From 1970 to 2025, average winter temperatures rose in 98% of the 244 U.S. cities analyzed in a new report from research group Climate Central.
- In the cities with increases, winter temperatures rose nearly 4° on average.
- Places with traditionally cold winters had the largest temperature increases, including Burlington, Vermont (+8.1°); Milwaukee (+7.3°); and Green Bay, Wisconsin (+7°).
Zoom in: In Phoenix, the average temperature climbed 3.1°.
The latest: A ridge of high pressure is building over the Western U.S., keeping temperatures well above normal across the state this week, National Weather Service Phoenix meteorologist Isaac Smith told Axios.
- Tuesday's high at Phoenix Sky Harbor was 76, 10 degrees above normal for this time of year. Even warmer temperatures are forecast for the rest of the week.
- We'll be "flirting with 80 degrees" Thursday, Smith said.
Flashback: This Phoenix winter warm-up should feel familiar: December 2024 and 2023 had monthly average temperatures of 62 and 60 respectively.
- The historical average for December is 55.
What's next: Smith said above-average temperatures are forecast to continue for at least two weeks.
Pro tip: We hope you took advantage of last week's sweater weather, because short sleeves look to be on the docket for the foreseeable future.
Reality check: It could be worse. The hottest December temperature on record was 87 in 1950, Smith said.