Arizona Air Quality Information

May 22nd in Phoenix: Coolest in 100 years; best ozone on record?


If you have been outside at all over the past few days, you might have noticed it doesn't exactly feel like the end of May. The reason? The storm track has been over Arizona, which has not allowed high-pressure to set up for any length of time that usually leads to periods of hot weather and poor air quality.

This trend will not end soon as another strong storm system will move through Arizona tomorrow (Wednesday). The forecast high temperature in Phoenix on Wednesday is only 74 degrees, which would tie the record for the second coolest May 22nd (the record is 71º set in 1919). To look at this another way, the forecast high temperature is closer to the average low for this time of year, which is only 3 degrees cooler, coming in at 71 degrees!

This weather pattern has also resulted in below average ozone for most of May. Tomorrow in Phoenix, ozone is forecast to be 47 AQI (51 parts per billion) which would be the 2nd lowest ozone value recorded in the Valley on May 22nd. The average ozone for this time of year is 77 AQI (63 parts per billion). So far this year, ozone has only exceeded the federal health standard in Phoenix two times. By this same time last year, Phoenix had exceeded 11 times.

[View the hourly air quality forecast for Phoenix]

The good news is, if you have liked the weather lately, there are indications that the pattern will remain active with below average temperatures and ozone values through the end of May.