* WHAT. High temperatures in the upper 90s to 105 expected. Low temperatures in the upper 60s to upper 70s near the foothills. * WHERE. San Bernardino and Riverside County Valleys-The Inland Empire. * WHEN. Until 8 PM PDT Monday. * IMPACTS. Heat related illnesses increase significantly during extreme heat events. * ADDITIONAL DETAILS. A few degrees of cooling are expected Friday, followed by warming for the weekend.

* WHAT. Dangerously hot conditions with high temperatures 90 to 97 degrees expected. Low temperatures in the upper 60s to upper 70s. * WHERE. Santa Ana Mountains and Foothills. * WHEN. Until 8 PM PDT Monday. * IMPACTS. Heat related illnesses increase significantly during extreme heat events. * ADDITIONAL DETAILS. A few degrees of cooling are expected Friday, followed by warming for the weekend.

* WHAT. High temperatures in the upper 80s to upper 90s below 5000 feet expected. Low temperatures in the mid 60s to mid 70s below 5000 feet. * WHERE. Riverside County Mountains and San Bernardino County Mountains. * WHEN. Until 8 PM PDT Monday. * IMPACTS. Hot temperatures may cause heat illnesses. * ADDITIONAL DETAILS. Well above average high and low temperatures are expected through the weekend.

* WHAT. Dangerously hot conditions with high temperatures in the upper 90s to 105 expected. Low temperatures in the upper 60s to upper 70s near the foothills. * WHERE. San Bernardino and Riverside County Valleys-The Inland Empire. * WHEN. Until 8 PM PDT Monday. * IMPACTS. Heat related illnesses increase significantly during extreme heat events. * ADDITIONAL DETAILS. A few degrees of cooling are expected Friday, followed by warming for the weekend.

* WHAT. High temperatures in the upper 80s to upper 90s below 5000 feet expected. Low temperatures in the mid 60s to mid 70s below 5000 feet. * WHERE. Riverside County Mountains and San Bernardino County Mountains. * WHEN. Until 8 PM PDT Monday. * IMPACTS. Hot temperatures may cause heat illnesses.

* WHAT. Dangerously hot conditions with high temperatures 90 to 97 degrees expected. Low temperatures in the upper 60s to upper 70s. * WHERE. Santa Ana Mountains and Foothills. * WHEN. Until 8 PM PDT Monday. * IMPACTS. Heat related illnesses increase significantly during extreme heat events. * ADDITIONAL DETAILS. A few degrees of cooling are expected Friday, followed by warming for the weekend.

* WHAT. Dangerously hot conditions with temperatures up to 99 possible. * WHERE. Eastern San Fernando Valley, Interstate 5 Corridor, Santa Barbara County Interior Mountains, Santa Clarita Valley, Santa Lucia Mountains, Santa Ynez Mountains Eastern Range, Santa Ynez Mountains Western Range, Western San Fernando Valley, and Western San Gabriel Mountains and Highway 14 Corridor. * WHEN. From Saturday morning through Monday evening. * IMPACTS. There is a high risk for dangerous heat illness for anyone, especially for the very young, the very old, those without air conditioning, and those active outdoors.