High temperatures expected Friday -- amid mostly sunny skies and following dense morning fog -- were 73 to 78 degrees at the beaches, 83 to 88 degrees inland, 86 to 91 degrees in the western valleys, 93 to 98 degrees near the foothills, 93 to 100 degrees in the mountains and 109 to 114 degrees in the deserts, according to the National Weather Service.
A NWS excessive heat warning for the deserts will take effect at 10 a.m. and extend until 8 p.m. Sunday. A less severe heat advisory for the valleys and for mountain locales lower than 6,000 feet will run concurrently.
“The first heat wave of the season will impact Southern California this weekend,'' according to the weather service. “The effects of the excessive heat will be magnified since high temperatures toward the end of May were below average. High temperatures will be around 15 to 20 degrees above average today and Saturday.''
Cal Fire is concerned the elevated temperatures, dry conditions and incredible amount of dry vegetation around the county could add up to a major fire.
"We actually moved into peak staffing on May 30. What that means, is that every one of our fire stations are covered, our 26 engines are covered and our air attack tankers are up and running," said Cal Fire Captain Kendal Bortisser.
Capt. Bortisser is also advising residents not to use weed whackers or mowers that could spark a fire.
He says it is important to draw up an evacuation plan, and be ready to go with important documents and medications should an evacuation order is set in place.
The NWS urged residents to protect themselves and their loved ones against dehydration, heat stroke and other heat-related illnesses. They were advised to stay well-hydrated, avoid working in the sun, check on neighbors and relatives -- especially the elderly -- and provide plenty of water to pets and livestock.
Residents were also urged to never leave a child, an elderly person, or a pet in a vehicle parked in the heat as interior temperatures can quickly reach lethal levels.
Forecasters said cooling would begin Sunday, but high temperatures would still be above average.