Statewide Flex Alert issued on Labor Day weekend, some areas in SoCal expect triple-digit temps

A statewide Flex Alert was issued for a portion of Labor Day weekend as another heat wave is about to grip Southern California, creating a high risk of heat-related illnesses and threatening big wildfires and power outages, the National Weather Service said Thursday.

"Dangerous heat" is expected from Friday through Labor Day, the NWS warned on its website.

California Independent System Operator issued a statewide Flex Alert, which calls for voluntary electricity conservation, beginning Saturday, September 5 and extends through Monday, September 7, from 3 p.m. to 9 p.m. daily.

Woodland Hills is forecast to hit highs 115 degrees Sunday, when Antelope Valley cities will reach 111 and Saugus 112, according to the NWS.

Get breaking news alerts in the FOX 11 News app. Download for iOS or Android.

An excessive heat warning issued by the NWS will be in effect from 10 a.m. Friday until 8 p.m. Monday in the San Gabriel and Santa Monica mountains, and the San Fernando, Santa Clarita, San Gabriel and Antelope valleys. In Orange County, the warning will be in force in coastal areas from 10 Saturday morning until 8 p.m. Monday.

"Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities." warned an NWS statement.

"Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors," it said, adding that children, seniors and pets must never be left unattended in vehicles under any circumstances in since temperatures can quickly turn lethal in the current conditions.

"Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose-fitting clothing when possible."

The weather service noted that the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments.

The high heat is being attributed to high pressure, which was centered near the California-Nevada border Wednesday evening and is forecast to settle into the Great Basin area through the weekend.

Cooling centers in Los Angeles County will be open, some beginning Thursday and others Friday through the weekend:

• Quartz Hill Library, 5040 W. Avenue M-2, open Thursday and tomorrow, noon-6 p.m.;
• El Monte Community Center, 3130 Tyler Ave., open Saturday and Sunday, noon-6 p.m.;
• Griffith Manor Park, 1551 Flower St., Glendale, open Friday through Tuesday, 10 a.m-6 p.m.;
• Pacific Community Center, 501 S. Pacific Ave., Glendale, Saturday through Monday, 10 a.m.-6 p.m.;
• Chimbole Cultural Center, 38350 Sierra Highway, Palmdale Thursday through Tuesday, noon-6 p.m.;
• Las Palmas Park, 505 S. Huntington St., San Fernando, Friday through Tuesday, 10 a.m. - 7 p.m.;
• Buena Vista Library, 300 N. Buena Vista St., Burbank, Friday through Monday, noon-6 p.m.;
• Robinson Park, 1081 N. Fairs Oaks Ave., Pasadena, Friday through Monday, 9 a.m.-6 p.m.

Cooling centers in Orange County will be open, some beginning Thursday and others Friday through the weekend:
• Brookhurst Community Center, 2271 W. Crescent Ave. 714-765-3373
• Canyon Hills Library, 400 Scout Trail, 714-974-7360
• Central Branch Library, 500 W. Broadway, 714-765-1880
• Downtown Anaheim Community Center, 250 E. Center St. 714-765-4500
• East Anaheim Library, 8201 Santa Ana Canyon, 714-765-3887
• Euclid Branch Library, 1340 S. Euclid, 714-765-3625
• Haskett Branch Library, 2650 W. Broadway, 714-765-5075
• Ponderosa Joint Use Library, 240 E. Orangewood Ave., 714-740-0202
• Sunkist Branch Library, 901 S. Sunkist, 714-765-3576
• West Anaheim Youth Center, 320 S. Beach Blvd., 714-765-6400

Fountain Valley:
• The Center at Founders Village-Senior and Community Center, 17967 Bushard Street, 8:30 am-4:00 pm Monday-Friday;

Garden Grove:
• H. Louis Lake Senior Center, 11300 Stanford Avenue, 11 a.m. to 5 p.m.;

La Habra:
• 101 West La Habra Boulevard, 8 am -5 pm Friday - Sunday;

Laguna Woods:
• 24264 El Toro Road, 8 am-5 pm Monday-Friday;

La Palma:
• Cool Center at the La Palma Police Department, 7792 Walker Street, Hours vary, call for more information 714-690-3370;

Newport Beach:
• Newport Coast Community Center, 6401 San Joaquin Hills Rd., 9 a.m. to 5 p.m.;

Seal Beach:
• Marina Community Center, 151 Marina Drive, 11:00 am., Saturday and Sunday;

Sunny skies were forecast in valley areas of L.A. County Thursday but partly cloudy conditions were expected nearer the coast, along with highs of 75 degrees at LAX; 80 in Avalon; 82 in Long Beach; 83 in Downtown L.A.; 90 in San Gabriel; 91 in Burbank; 92 in Pasadena; 97 in Saugus and Woodland Hills; and 102 in Palmdale and Lancaster. Temperatures will be up to eight degrees higher Friday, up to 11 degrees higher than that on Sunday, then begin a sharp decline, though by Wednesday several communities will still be in the 90s -- 98 in the case of Woodland Hills.

The NWS forecast sunny skies in Orange County Thursday and highs of 74 in Laguna Beach and San Clemente; 75 in Newport Beach; 84 on Santiago Peak; 85 in Fullerton, Irvine and at Fremont Canyon; 86 on Ortega Highway at 2,600 feet; 87 in Yorba Linda, Anaheim and Mission Viejo; and 89 at Trabuco Canyon. Coastal communities will climb up to 109 Saturday, about the same as inland communities, which is unusual. By Wednesday, Mission Viejo will reach 90 degrees but all other locales will be in the 80s, except at the coast, which will have reverted to the high 70s, according to an extended NWS forecast.