© CBS 5PHOENIX (CBS5/AP) -
Extreme August heat is in the forecast for the week ahead, helping prompt a high pollution advisory for ozone for the Phoenix area.
A strong high pressure ridge is building over the southwestern U.S., resulting in unusually warm temperatures, even by desert standards.
That is why an excessive heat warning is in effect for the Valley through Thursday as daytime highs reach the 110- to 115-degree range, with overnight lows only bottoming out around 90 degrees.
On Wednesday, there was a record afternoon heat, as Phoenix hit 114 degrees, breaking the previous daily record of 113 degrees last set in 1991.
Look for small chances of mainly late afternoon/evening thunderstorms through the end of the week.
The Arizona Department of Environmental Quality said they had some of the highest ozone readings of the season on Tuesday and high temperatures are expected to continue.
Ozone is an invisible gas created when other pollutants in the air - such as those created by combustion - are heated by the sun.
Experts say ozone can irritate the lungs and aggravate existing health conditions such as asthma.
Maricopa County officials have called Thursday a mandatory no-burn day.
Copyright 2012 CBS 5 (Meredith Corporation). All rights reserved. The Associated Press contributed to this report.
