Back-to-back haboobs blanketed Phoenix with dangerous levels of dust

Two late-night dust storms that swept across the Phoenix area last week were among the most intense to hit the region in years, reaching the highest level on a severity scale developed by Arizona State University researchers.

Both haboobs were classified as Category 5 storms, with wind speeds of about 50 mph and high concentrations of dust. According to The Associated Press, they were only the fifth and sixth storms in the past 16 years to reach that level.

Ryan Heintzman, an assistant teaching professor in ASU’s School of Geographical Sciences and Urban Planning, helped create the Phoenix Dust Storm Scale.

“The way that the scale works is … it’s just the concentration of dust in the air,” Heintzman told KTAR News 92.3 FM’s Outspoken with Bruce & Gaydos on Friday. “One through five are still high levels of dust that you won’t really want to be breathing in for a prolonged period of time and a five is five times as much dust in the air than one.”

What are haboobs?

The first storm struck late last Monday, followed by another early Thursday. Both reduced visibility to about a half-mile and left a lingering brown haze the following mornings.

Haboobs form when strong downdrafts from thunderstorms stir up loose dust and dirt, pushing it ahead of an approaching storm cell. They can create massive walls of dust that sharply reduce visibility, endanger drivers and cause health problems.

Here are some photos of a haboob that hit the Phoenix area on August 25, 2025:

How did last week’s dust storms affect the Phoenix area?

Heintzman, who helped create the Phoenix Dust Storm Scale, said the late-night timing of last week’s storms likely reduced their impact.

“It definitely was a good thing that these happened late at night. We have seen some in the past that have happened during the day,” Heintzman explained. “These happened late at night, and woke some people up, including me.”

He said the hot, dry conditions over the past couple of weeks allowed dust around Phoenix to be picked up more easily.

“When these dust storms come through, we get rain that comes after, but that hasn’t happened with these category fives, and so that’s allowed for the dust to stay at high concentrations and linger for many hours,” Heintzman said.

Monday night’s storm, which stretched into the next day, lasted for a record of 16 hours, he added.

“We have between five and 15 [haboobs] a year, and this year, we’re about at eight, I think, with this most recent one,” Heintzman said. “They’ve been bigger, but that could be all we have. I’m hoping we get a little bit more rain and a little less dust in the coming weeks.”

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