A record-breaking winter of warmth covers Tucson, the West

The period of December 2025 through February 2026 (the National Weather Service's definition of winter for record-keeping purposes) saw Tucson averaging 59.3 degrees. That's 5 degrees above the normal wintertime average temperature and 1.4 degrees above the average temperature during the previous record-setting winter of 2017-'18, the weather service says.

In addition, this was the first Tucson winter since records started being kept here in 1894 when no frosts were recorded at the city's official weather station, which today is Tucson International Airport. In an average year, the mercury drops to 32 degrees or lower on 10 days.

Exceptionally warm days played a bigger role in the season's record warmth than warmer-than normal nights. The winter's average high temperature of 72.2 degrees was 5.2 degrees above normal while its average low temperature of 46.4 degrees was 4.9 degrees above normal.

The warmth was triggered by a complex series of causes including human-induced climate change, said  Michael Crimmins, a University of Arizona climate scientist.

In all, Tucson experienced 13 days of record warm temperatures this winter — 7 for daytime highs and 6 for nighttime lows, the National Weather Service said in its monthly online climate report for February. The wintertime record-setting climaxed on Feb. 27th and 28th, with highs of 89 degrees.

That was followed by another record-setting day of 89 degrees on March 1 and a 90-degree March 2, which was a degree below the record-setting March 2 of 1910 and 2009, said weather service meteorologist Chris Rasmussen.

The weather service defines seasons for measuring average temperatures by using three specific months. The actual winter for 2025-26 runs from Dec. 21 to March 20.

Rainfall for the season was 2.15 inches, almost a half-inch below the norm of 2.64 inches, the weather service said.

The freakishly warm winter had three root causes, said Crimmins. First, the West experienced La Niña conditions, a meteorological phenomenon typically associated with warmer, drier weather in the Southwest and cooler, wetter weather in the Pacific Northwest, he said.

Second, periodic disruptions occurred of "polar vortex" conditions that otherwise would cause the polar-based jet stream to dip farther south than normal across the Northern Hemisphere, he said.

Typically in winter, the polar jet stream "is the main player across north America," Crimmins said.

Third, long-term temperature trends driven by human-caused climate change make these warm winters that emerge from natural variability even warmer, he said. That increases the magnitude and frequency of broken temperature records.

Tucson's record warmth was matched across much of the West, where record-setting warm winters prevailed at every main weather station in Arizona, in much of Utah and as far north as southern Idaho, said Crimmins. The Northern Rockies areas of southern Idaho and northern Utah were particularly toasty, a weather map prepared by Crimmins shows.

Phoenix obliterated its year-old record warm winter temperatures this time around by almost 3 degrees, while Albuquerque's winter topped its past record by 3 full degrees, said weather.com, the website for the Weather Channel cable network.

Across southern Idaho, wintertime temperatures reached 9 to 10 degrees above average, and at one weather station 12 degrees above, said Crimmins, pronouncing those temperatures "bonkers." His map also showed a northeast Utah weather station averaged 14 degrees above normal for the past winter.

Looking ahead at Tucson's spring temperatures, expect more of the same warmth although not necessarily record-setting warmth.

The high temperature Friday, March 6, will cool down to 69 degrees, and some chances of showers exist for late Sunday and Monday. But the entire month of March and the entire spring are projected by the weather service to average out at warmer-than-normal temperatures.

For March, a 49% chance exists of warmer-than-average temperatures and only a 16% chance of cooler-than-normal temperatures. For the spring through the end of May, the weather service projects a 58% chance of unusually warm weather and only a 9% chance of unusually cool weather.

"Having weather we normally experience in May happen in February makes spring seem a lot warmer," said Crimmins, adding he can't predict if Tucson will get yet another summer of extreme heat at well above already scorching average summertime temperatures. The city's summer of 2025 tied for its hottest summer on record, and four of the last five summers ranked among Tucson's hottest on record.

"But we still don’t know how extreme it will be," he said.