Triple-digit temperatures will arrive in parts of Southern California on Wednesday as a heat wave descends, exacerbating the woes of firefighters who already are batting a number of wildfires across the region. The spike in heat is expected to peak Thursday and taper down by Friday evening, forecasters say.

A significant warm-up is coming to much of Southern California with triple-digit heat expected to scorch parts of the valleys and Inland Empire. Temperatures will remain normal through Tuesday with a gradual increase on Wednesday. Forecasters predict conditions will peak on Thursday.

A heat wave is predicted to begin this Wednesday and run through Saturday. It is expected to peak on Thursday with some areas reaching temperatures in the triple digits. The cause is a high-pressure system,

The Santa Clarita Valley and Inland Empire will experience the worst air quality on Tuesday, according to South Coast AQMD.

Under a Code Orange alert, it's recommended that children, older adults and those with respiratory illnesses limit time spent outdoors.

Millions of Americans across the Midwest, Northeast and swathes of the South and Southwest are under air quality alerts Monday. Newsweek's live blog is closed.