Valley makes history with two Class 5 haboobs in same week

• The previous 16 years had seen only four other Class 5 haboobs, ASU professor Randall Cerveny tells Axios, "and here we've had two Class 5's, one right after the other."
• The other Category 5 storms occurred in 2011, 2013, 2023 and last September.

How it works: The dust storm scale, which ASU unveiled earlier this year, rates haboobs by one-hour average dust concentrations, and also categorizes storms by spatial coverage, duration and wind gust levels.

• Storms are measured on micrograms of particulate matter per cubic meter. A microgram is smaller than the diameter of a human hair.
• The Air Quality Index uses the same measurement, with zero to 50 micrograms of particulate matter per cubic meter being considered "good."

Stunning stat: Monday night's storm had a maximum dust concentration of 6,136 micrograms per cubic meter, the second highest ever recorded in the Valley.

• Thursday's storm, which arrived around 1am, was close behind.

What they're saying: "Probably we were one of the poorest air-quality places in the entire world (Thursday) morning as this dust storm rolled through," Cerveny says.