Three EF-1 tornadoes touched down in Arizona during a storm outbreak that ran from October 20 to 22, 2026, and each one produced winds over 100 mph. The National Weather Service office in Phoenix called the outbreak the most significant severe weather event in the state since early October 2010. Two supercell thunderstorms also crossed the Phoenix metropolitan area, one over Chandler and Mesa and a second over the central city, dropping hail up to two inches across.
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The tornadoes themselves stayed out of the valley. They struck high country, while the metro area took its damage from hail and straight-line wind.
Wing Mountain, Heber-Overgaard and Spruce Mountain
NWS Phoenix lists the three confirmed EF-1 tornadoes near Wing Mountain, northwest of Flagstaff; in the Heber-Overgaard area of Navajo County; and near Spruce Mountain, south of Prescott in Yavapai County. The write-up gives no path lengths or touchdown times for any of them, so the public record of how far each one ran is thinner than the ratings suggest. The summary credits photographs to trained storm spotter Brandon Knapp, to the Phoenix television stations ABC 15 and FOX 10, and to several residents who posted to Facebook, so much of the documentation came from people who were standing near the storms.
An EF-1 rating is a statement about damage. The Enhanced Fujita Scale assigns EF-1 to tornadoes with estimated peak gusts of 86 to 110 mph, and surveyors reach the number by matching what a tornado broke against a list of damage indicators rather than by measuring wind directly. That is why the office can say the storms produced winds over 100 mph without any anemometer having recorded it: the estimate comes from the debris. All three sit in the upper half of the EF-1 band by that reading.
Tornadoes of any strength are unusual in Arizona, and the northern and central highlands are where most of the state’s few arrive. Forecasters at the NWS offices in Flagstaff and Phoenix split the warning duty between them, with the northern half of the state placed under a tornado watch on the afternoon of October 21.
Two supercells over the Phoenix valley
The first valley storm formed near Maricopa in northwestern Pinal County on the evening of Tuesday, October 20, then moved northeast toward Chandler and Mesa. Radar followed the supercell from 9:12 to 10:58 PM MST. NWS Phoenix reports hail from 1 to 2 inches in diameter and numerous uprooted trees, including an estimated 25 to 30 trees at a park in Chandler near Rural Road and Chandler Boulevard. In Mesa, about five large trees came down at a church, and falling limbs damaged carports and vehicles at an apartment complex near Gilbert Road and University Drive.
A second supercell followed on Wednesday afternoon. It started south of Avondale, moved north past the Estrella Mountains and tracked along Interstate 17 between 2:19 and 4:38 PM MST. Hail reached 2 inches and possibly larger, denting vehicles, shattering auto glass and breaking residential windows. Winds in excess of 60 mph uprooted more large trees, and one fell onto a vehicle at an apartment complex near Peoria Avenue and Interstate 17.
A rare enhanced risk and the first tornado watch since 2010
The forecast side of the event was unusual too. At 9 AM MST on October 20, the Storm Prediction Center placed parts of south-central and north-central Arizona under a slight to enhanced risk of severe storms, which NWS Phoenix says was the state’s first enhanced risk since September 2019. The center also introduced a hail intensity flag, signaling that stones larger than 2 inches were possible.
On October 21 the Tornado Watch for northern Arizona was the first the state had seen since October 2010, and a Severe Thunderstorm Watch covered south-central and east-central areas. Watches stayed in effect into October 22. NWS Phoenix, Flagstaff and Tucson hosted live webinars for emergency managers, and the Phoenix office began public messaging with a weather-story graphic on October 17, three days before the first storm.
Moisture, shear and the warning count
The ingredients were as unusual as the watches. Precipitable water, the total moisture in a column of air, exceeded 250 percent of normal and set late-October records, at 1.0 to 1.4 inches at higher elevations and 1.5 to 1.7 inches at lower ones. Deep-layer wind shear topped 50 knots, with southeasterly surface winds veering south-southwesterly aloft, the kind of twist that lets thunderstorms rotate. Heavy rain fell, but the fast storm motion limited flooding. Instability peaked at 1,000 to 1,500 joules per kilogram, and temperatures about 18,000 feet up were near minus 10 Celsius, cold enough to help hail grow.
By the office’s tally, the three days produced 158 Severe Thunderstorm Warnings, 16 Tornado Warnings and 11 Flash Flood Warnings. Only three of those 16 tornado warnings are tied to a confirmed tornado in the NWS summary, and the document reports no injuries or deaths. The 2010 benchmark the office uses is the October 5, 2010 outbreak, which produced the largest hail recorded in Phoenix and has its own write-up on the NWS site. What the 2026 account leaves open is the damage total: no dollar figure for the hail, the toppled trees or the broken glass appears in the NWS account.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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