Extreme Heat Warning

* WHAT...Dangerously hot conditions with temperatures up to 100.

* WHERE...Santa Ana Mountains and Foothills.

* WHEN...Until 8 PM PDT this evening.

* IMPACTS...Heat related illnesses increase significantly during extreme heat events.

* ADDITIONAL DETAILS...Low temperatures 5 to 10 degrees above normal will limit overnight relief from the heat and will increase the threat of heat-related illness.