Temperatures reached triple-digits in six spots in Los Angeles County, topped by Woodland Hills which set a record for the date of 105 degrees.
The other locations where the high was at least 100 was Northridge (104), Chatsworth (103), Van Nuys (101), Pasadena (100) and Saugus (100), according to the National Weather Service.
The previous record in Woodland Hills for Oct. 15 was 104, set in 1974.
The 86-degree high in Sandberg in the Antelope Valley tied the high for the date set in 1991.
Other Los Angeles County highs for Thursday include 97 in Burbank, 95 at Long Beach Airport and 92 in downtown Los Angeles, Acton and Lancaster.
The National Weather Service is crediting the hot temperatures to high pressure aloft combined with offshore flow.
A fire weather watch will be in effect from late Thursday through Friday afternoon in the San Gabriel Mountains, Angeles National Forest, Santa Clarita Valley and areas of Ventura County amid high temperatures, humidity levels as low as 6% and Santa Ana winds of 20-30 miles per hour, generating gusts of 35 to 45 miles per hour.
A fire weather watch means that critical fire weather conditions are forecast to occur.
Red flag warnings indicating critical fire weather conditions will occur was issued for 3 a.m.-6 p.m. Friday for the Santa Clarita Valley, Angeles National Forest, Los Angeles County mountains,
A heat advisory will be in effect until 5 p.m. Friday along the Los Angeles County coast, in Malibu, Santa Monica and other beach cities, in downtown Los Angeles, Hollywood, Beverly Hills, the San Gabriel and Santa Monica mountains, the San Fernando, Santa Clarita and San Gabriel valleys, and inland Orange County, indicating temperatures could threaten human health.
“Hot temperatures may cause heat illnesses to occur,” warned a weather service statement. “Those without air conditioning will be especially vulnerable during this extended heat wave. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.”
The weather service stressed that children, seniors and pets should never be left unattended in vehicles under any circumstances, even with windows open as car interiors can quickly turn lethally hot.
The continued hot weather prompted the California Independent System Operator, which manages the state’s power grid, to issue a Flex Alert that will be in effect until 10 p.m. The alert urges residents to voluntarily cut their power to prevent strain on the grid, which could potentially lead to rolling power outages.
Residents were urged to take steps to cut power, such as delaying the use of major appliances, turning off unnecessary lights and closing curtains and drapes to cool homes.
Yorba Linda was the hottest spot in Orange County at 100. Other Orange County highs included 99 in Anaheim, 98 at the Fullerton Airport, 97 in Santa Ana and Lake Forest and 92 at John Wayne Airport.