A record-strong El Niño event developing in the Pacific Ocean could bring much-needed moisture to Arizona in the months ahead.
El Niños occur every few years when water warms in the Pacific. But this year, ocean temperatures have been historically hot, and the supercharged El Niño forming as a result is expected to upend weather patterns across the globe.
“This one is crushing records we have in historical databases,” said Michael Crimmins, professor and extension specialist in the Department of Environmental Science at the University of Arizona.
During years with strong El Niño events, the pacific jet stream tends to shift south, pushing more storm systems than usual across the southern U.S., including Arizona. Crimmins said that change in the storm track could begin in October or November and could continue through winter and early spring.
“It certainly does shift the odds that we will see above-average precipitation [in Arizona] coming up this winter, but it's not a guarantee,” Crimmins said.
Crimmins noted that the last time there was a strong El Niño, in 2016, storms stayed farther north and much of Arizona actually ended up with drier-than-normal winter weather.
Long-range forecasts from the National Weather Service Climate Prediction Center show most of Arizona has a 33% to 60% chance of above-normal rainfall throughout winter months.
Crimmins expects the best chances for rain will come in early 2027.
“The bulk of that storm activity, when we really do see those storms stack up, is usually January, February, and March,” Crimmins said. “We know in these past [El Niño] events we'll have these weeks where we'll just have runs of storms and they'll just run into Arizona over and over again, and then we will have breaks between these wet periods, it'll get sunny.”
But even with odds tilting toward a wetter winter and spring, Crimmins said it's difficult to predict when storms might develop and how strong they could be.
“Some of that precipitation could be extreme in the way it comes,” Crimmins said. “But if everything's spaced out right, this could be just a really beneficial wet period for Arizona as well.”
A season of above-average precipitation would be welcome in Phoenix, where rainfall has been well below-normal so far in 2026. Typically, by early September, Sky Harbor International Airport would have received nearly 5 inches of rain. This year, just 1.73 inches of rain have been recorded, according to National Weather Service data.
But a potentially wet winter could also increase flood risks across the state, Crimmins said.
“It's certainly something we should be vigilant about this upcoming winter as well, especially if everything's pointing to above-average [precipitation],” Crimmins said. “We're trying to get the message out that this is coming, it's here, pay attention.”
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