Heat leads to ozone advisory for San Bernardino Valley, Lake Arrowhead, Coachella Valley

The South Coast Air Quality Management District Thursday issued an ozone advisory for much of the South Coast Air Basin and Coachella Valley due to the heat wave.

Temperatures over the weekend will reach highs in the 100s in the Inland Empire and 110s in the Coachella Valley, according to the National Weather Service, which issued excessive heat warnings and watches for parts of the South Coast Air Basin and the Coachella Valley.

Levels of ground-level smog may reach the unhealthy level at times through Tuesday in parts of the South Coast Air Basin and in the Coachella Valley, according to AQMD spokesman Bernard Parks.

Ozone levels will be highest in inland areas, including the Lake Arrowhead area, San Bernardino Valley and nearby areas.

The persistently high ozone levels are in part caused by high temperatures that increase ozone formation rates and emissions of chemicals leading to ozone formation.

The advisory will be in effect from 10 a.m. Friday through 8 p.m. Tuesday.