It is difficult to describe how bonkers this week’s heat wave is in the southwestern United States. Alan Gerard, a typically even-keeled meteorologist with 35 years of forecasting experience under his belt, attempted to do so in a recent edition of his newsletter, Balanced Weather. He settled on: “jaw-dropping,” “insane,” “truly historic,” “literally flabbergasting,” “incredible,” and “anomalous [even for] the middle of summer.”

Jeff Berardelli, the chief meteorologist at WFLA, the NBC affiliate in Tampa, tried to contextualize it on social media, noting that based on historical patterns, Phoenix could expect a March day as hot as it was on Thursday — 105 degrees Fahrenheit — only once every 4,433 years.

Phoenix is just one part of the story. The heat wave — which began ramping up on Tuesday, peaks Friday, and won’t subside until early next week — has set or tied March record highs in at least 480 locations so far, stretching from New Mexico to Southern Oregon. California has already broken the record for the hottest winter day ever recorded anywhere in the U.S.: 109 degrees on Thursday at a station in the eastern Coachella Valley. “The extent and magnitude of this particular heat wave is without comparison to anything that we’ve seen in March,” John Abatzoglou, a professor of Climatology at the University of California, Merced, who specializes in climate impacts in the West, told me.

That’s partially because this heat wave would be “virtually impossible for the time of year in a world without human-induced climate change,” per a report released Friday by scientists from World Weather Attribution. Heat waves have one of the clearest climate signals of any extreme weather event because a hotter planet means a hotter baseline. “Across almost the entire western U.S., temperatures [this week] were made at least five times more likely due to climate change,” Zachary Labe, a climate scientist at Climate Central, which maps the effects on daily temperatures, told me.

The March 2026 heat wave is likely to become a reference point in the same vein as the 2021 heat dome in the Pacific Northwest, subject to study, research, and scrutiny by climatologists, public health experts, hydrologists, and emergency managers in the months and years to come. The consequences of the current heat wave will also outlast the record temperatures. When it is this hot — and, more importantly, when it is this hot this soon — the effects compound, touching everything from hydropower capacity to the coming wildfire season. (Read more from “A Once-in-a-4,433-Year Heat Wave Is Hitting the Western U.S.” HERE)

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