Overview
- A powerful outflow-driven dust storm that moved into Pinal and Maricopa counties late Monday night was rated Category 5 on ASU’s PHX‑DUST Scale with peak PM‑10 readings above 6,000 μg/m³ in places.
- The National Weather Service and the Arizona Department of Environmental Quality issued air‑quality alerts for elevated coarse particulates that can aggravate heart and lung disease, and officials warned sensitive groups to stay indoors.
- Sky Harbor recorded gusts near 48 mph as the storm passed, reducing visibility, disrupting road safety and helping fuel a brush fire that spread to vacant buildings in south Phoenix.
- An Extreme Heat Warning for the Phoenix area has been extended through at least Friday with highs forecast to top 110°F, and officials urged people to use cooling centers, hydrate and avoid outdoor exertion.
- Forecasters expect monsoon humidity to rise and isolated storms to return across southern and southeastern Arizona with a renewed risk of gusty outflows and more blowing dust before pollutant levels slowly ease later in the week.