* WHAT...High temperatures in the mid to upper 90s expected and overnight lows in the mid-70s.
* WHERE...Orange County Inland Areas and Santa Ana Mountains and Foothills.
* WHEN...From 10 AM Tuesday to 8 PM PDT Thursday.
* IMPACTS...Hot temperatures may cause heat illnesses.
* ADDITIONAL DETAILS...Moderate to major HeatRisk. Elevated low temperatures will limit overnight relief from the heat.