Extreme Heat Warning

* WHAT...High temperatures in the upper 80s and low 90s expected and overnight lows in the 70s.

* WHERE...Santa Ana Mountains and Foothills.

* WHEN...For the Extreme Heat Warning, until 8 PM PDT Wednesday. For the Heat Advisory, from 8 PM Wednesday to 8 PM PDT Thursday.

* IMPACTS...Heat related illnesses increase significantly during extreme heat events. Hot temperatures may cause heat illnesses.

* ADDITIONAL DETAILS...Areas of Major HeatRisk. Very warm overnight temperatures will limit relief from the heat.