The temperature hit 109 degrees in Riverside and broke a 104-year-old record. The mercury also hit 109 degrees in Woodland Hills, shattering the old record of 108 degrees set in 2006.
Desert heat broke records Friday as well. Palm Springs reached 122 degrees, Indio hit 119 and Thermal peaked at 121 degrees.
WATCH LIVE: Get the latest on the SoCal heat wave on ABC7
The National Weather Service expected to see heat records set or matched Friday in parts of the Los Angeles Basin. It issued an excessive heat warning in the valleys and more inland parts of the area.
The blistering, potentially life-threatening heat caused communities in Santa Clarita to designate three libraries and a senior center as cooling sites.
"You can read a book, you can play some games, you can get on the computer and have more of sanctuary to be cool and to be safe so you don't experience any of the heat related issues that will occur," said librarian Matthew Hortt
People in the area could not cool off at local swimming spot Vaquero Beach. The Pyramid Lake site was off-limits because of an outbreak of blue-green algae. Health experts said exposure to the organisms can cause vomiting, diarrhea and flu-like symptoms.
Temperatures reached as high as 103 in the San Gabriel Valley Friday, forcing children, adults and even pets to combat the weather in their own ways.
Kids at the Tom Sawyer Summer Camp in Pasadena used a Slip 'N Slide to beat the heat.
"This is really enjoyable because you get to get all wet and you're not as hot," said camper Gabriella Rouveyrol.
Local dog owners watched their pets congregate under a big tree for shade in a popular off-leash park in Pasadena.
"We try to come a little earlier during the very hot days for the dogs sake, so they can get their play in because then they sleep all afternoon after that," said Ann Voyer.
The city of Monrovia closed Canyon Park to hikers on Friday and Saturday. A Home Depot down the street from the park made sure 'fans and portable air conditioners' were easy to find by the store's front entrance.
Health experts caution people to not overexert themselves, to check on older neighbors and relatives and to stay hydrated during the heat wave.