The main weather story, at least through Sunday, will be the heat. The National Weather Service has issued an Extreme Heat Warning for the lower deserts of southeastern Arizona, valid through Sunday. This is a result of the monsoonal high pressure camping out directly overhead.

However, by Monday, the high is expected to start flattening out a bit, resulting in a flow more favorable flow for moving thunderstorms into Tucson. Thus, chances for storm-related weather (local gusty winds, rain, clouds) will increase again. Moisture will also increase, helping to shave off a few degrees from daytime high temperatures.

Air quality-wise, ozone will continue to be the main pollutant to watch during the current lull in the monsoon. Ozone is forecast in the Moderate AQI category each day. However, by Monday, ozone levels may drop if monsoonal thunderstorm weather enters the picture in the early afternoon again.

Lastly, PM10 (dust) and PM2.5 (smoke) will continue to be mostly locally driven each day. But, we can't rule out pockets of dust from winds from distant thunderstorms moving into the area in the evenings or overnight.

Check back again on Monday morning for the next Tucson Air Quality Forecast.

- M. Graves
ADEQ Meteorologist