* WHAT...Dangerously hot conditions with high temperatures on the hottest days ranging from around 90 near the coast to the upper 90s to 108 for the valleys possible. Low temperatures for coastal areas into the western valleys will warm into the lower to mid 70s during the weekend with those warm overnight temperatures continuing for next week.

* WHERE...Orange County Coastal Areas, Orange County Inland Areas, San Bernardino and Riverside County Valleys-The Inland Empire, San Diego County Coastal Areas, San Diego County Valleys, and Santa Ana Mountains and Foothills.

* WHEN...From Friday morning through Wednesday evening.

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

* ADDITIONAL DETAILS...A long-duration heat wave is expected to develop late this week and continue through much of next week into the following weekend with Moderate or greater HeatRisk for the coast and valleys and Major to Extreme HeatRisk for inland coastal areas into the western valleys.