Starting Wednesday, temperatures are expected to be in the high 90s and low 100s in inland areas. Officials say now is the time to prepare.

The report, released this week, found that 58% of fast-food workers surveyed in July said they had worked in excessive heat conditions in the last year. And nearly half, or 48%, reported experiencing heat illness symptoms including headaches, fatigue, dizziness, confusion, muscle pain or nausea.

Southern California Edison says high heat is not the only factor it monitors. The utility also tracks dry vegetation and humidity levels at its emergency operations center in Irwindale to determine if a public safety power shutoff is necessary to prevent wildfires.