Arizona Air Quality Information

Significant Fall Storm System Coming Soon


It's finally October, believe it or not, and that means we are in a "transition" season, meteorologically speaking. In other words, the atmosphere is actively changing to eventually reach it's winter state. But how do we know this? We know it by watching the jet stream--and by the weather forecast for early next week!

During the fall, the average position of the jet stream begins to shift southward from approximately the U.S./Canada border to the continental U.S. And since storm systems (i.e. low pressure systems) move along the jet stream, we usually see an increase in their frequency here in the Southwest by October.

Early next week, one such storm (seen in the above water vapor satellite image on Friday afternoon) is forecast to sweep through Arizona. This system is expected to be relatively strong, resulting in breezy conditions around the state on Monday and Tuesday, but especially on Monday. It will also pack a punch of cooler air, with high temperatures on Tuesday forecast to drop well below normal. For instance, highs in Phoenix, normally around 90°F, will be in the low 70s on Tuesday! That's chilly for those with Arizona blood. Overall, it's storm systems like these that help to carry out the "transition" from summer to winter.

Air quality-wise, the main concern with this storm will be the winds. Though parts of Arizona have seen some measurable rain in the last week, there is still a potential for winds to cause blowing dust. Phoenix will likely see elevated PM10 (coarse particulate matter) levels Monday and Tuesday afternoon. Yuma is also expected to experience blowing dust, but even more so because of stronger winds and drier soils.

View the Phoenix and Yuma Air Quality Forecasts here:
Phoenix Forecast
Yuma Forecast

The good news, however, is that ozone levels are expected to remain low. Average ozone levels have already fallen substantially because of shorter day lengths (ozone needs sunlight to form). But the upcoming storm system is also expected to help with dispersing ozone.