* WHAT...DANGEROUSLY HOT CONDITIONS WITH HIGH TEMPERATURES DURING THEPEAK OF THE HEAT ON THURSDAY AND FRIDAY IN THE UPPER 90S IN THE WESTERN VALLEYS TO 108 IN THE INLAND VALLEYS EXPECTED. LOW TEMPERATURES WILL BE MOSTLY IN THE 70S.

* WHERE...SAN DIEGO COUNTY VALLEYS.

* WHEN...UNTIL 8 PM PDT FRIDAY.

* IMPACTS...HEAT RELATED ILLNESSES INCREASE SIGNIFICANTLY DURING EXTREME HEAT EVENTS.

* ADDITIONAL DETAILS...LOW TEMPERATURES 5 TO 10 DEGREES ABOVE NORMAL WILL LIMIT RELIEF FROM THE HEAT. INCREASING TEMPERATURES THROUGH FRIDAY WILL INCREASE THE THREAT OF HEAT-RELATED ILLNESS ACROSS POPULATIONS.