Arizona Air Quality Information

The monsoon season is officially here on Saturday

On Saturday, June 15, the monsoon season officially begins. This means that Phoenix residents will soon start to see thunderstorms build in the distance and slowly make their way towards the Valley. But, we're still waiting for the monsoonal high pressure to set up over the Southwest, and this may not happen until near the end of this month.

Along with the beginning of the monsoon season also come reminders of the type of weather hazards we could encounter during the next few months: torrential rain, flooding, microbursts, strong wind gusts, hail, high rates of lightning, and of course, dust storms.

Air quality-wise, dust storms are the most obvious hazard, as dust can get lodged into the lungs and pose a risk to human health. Last year, there were 12 days during the monsoon season when PM10 (dust) exceeded the federal health standard because of dust storms.

But, let's not forget ozone, which, although invisible, can reach adverse levels for weeks at a time during the monsoon season. Last year, ozone exceeded the federal health standard on 37 days in Phoenix during the monsoon season. There were also two times when ozone exceeded the health standard at least 7 days in a row. In general, Phoenix typically sees some of its highest ozone levels during the monsoon season.