Punishing triple-digit heat continues to bear down on Southern California, with a fifth straight Flex Alert in effect Sunday urging residents to conserve electricity during peak hours.
Excessive heat warnings were extended until at least 8 p.m. Wednesday for the mountains and the Santa Clarita, San Fernando and San Gabriel valleys, along with the inland coastal area, including downtown Los Angeles.
The warning in the Antelope Valley will last until 9 p.m. Wednesday, with temperatures anticipated up to 113 degrees.
Forecasters also warned of possible monsoonal thunderstorms Sunday and Monday across the mountains, deserts and portions of the valleys. Potential threats include heavy downpours with localized flooding, strong wind gusts over 50 mph, hail, and frequent lightning.
The NWS called for a 20% chance of showers and thunderstorms Sunday afternoon in the San Gabriel, San Fernando, Santa Clarita and Antelope valleys.
The weather service reported a severe thunderstorm near Acton shortly before 3 p.m., moving west at 10 mph. Potential hazards included 60 mph wind gusts and quarter-size hail, with hail damage to vehicles expected.
Sunday’s high temperatures reached 104 in downtown Los Angeles, 107 in Pasadena, 108 in Lancaster and Sherman Oaks, 109 in North Hollywood and 110 in Van Nuys.
Long Beach’s high of 108 degrees broke the previous record of 107 set in 1988, according to the National Weather Service.
Record temperatures were recorded Saturday in Lancaster, Palmdale and Sandberg. Lancaster’s 109 was one degree higher than the previous record of 108 set in 1955. Palmdale’s 106 tied the record set in 1947 and in Sandberg, near the Grapevine, Saturday’s 99 degrees broke the previous record of 97 degrees, set in 1955.
In Orange County, excessive heat warnings are also in place through 8 p.m. Wednesday for coastal and inland areas and the Santa Ana Mountains and foothills. Orange County beaches were in the upper 80s on Sunday, with Anaheim reaching 105, Santa Ana expected to reach 103 degrees and Fullerton 107.
Overnight lows are not offering much relief either, staying in the 70s and even in the low 80s in some of the hotter areas.
“A prolonged period of very hot conditions with minimal coastal clouds is expected as high pressure aloft remains anchored over the West,” according to the National Weather Service. “Triple-digit heat will be common for many valley and mountain locations through early next week. Record-breaking heat will produce a very high risk of heat illness.”
“Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors,” the NWS urged. “Young children and pets should never be left unattended in vehicles under any circumstances.”
Forecasters also urged residents to be aware of the signs of heat stroke and to take precautions.
“Take extra precautions if you work or spend time outside,” according to the NWS. “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. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location.”
The California Independent System Operator — which manages the state’s power grid — issued the statewide Flex Alert from 4 to 9 p.m. Residents are urged to take the following power-saving steps:
— setting thermostats to 78 degrees or higher;
— avoiding use of major appliances;
— turning off unnecessary lights; and
— avoid charging electric vehicles.
Residents are also advised to pre-cool their homes as much as possible and close blinds and drapes to keep interiors cool.
The alerts have worked thus far, with the state avoiding involuntary power cutoffs. Officials said Sunday, Monday and Tuesday in particular are shaping up to be the most difficult days of the heat wave. Tuesday’s peak demand is forecast to be 50,087 megawatts, just shy of the all-time record of 50,270 set in 2006.
According to Cal-ISO, electrical demand on Saturday was 45,829 megawatts, and the forecast for Sunday was about 45,000.
Triple-digit highs are expected to last through most of the week, with no significant cooling until Saturday.
The five year-round pools operated by the Los Angeles County Department of Parks and Recreation, which are usually closed on Labor Day, will open on Monday because of the heat, the department’s Director Edith GarcÃa-Gonzalez told City News Service.
The Belvedere, Jesse Owens, Roosevelt, San Fernando and Castaic aquatic centers will be open Monday from 12:30-2 p.m., 2:30-4 p.m. and 4:30-6 p.m.
Cooling centers for Los Angeles County can be found at ready.lacounty.gov/heat/. Cooling centers for the city of Los Angeles can be found at emergency.lacity.org/la-responds/beat-heat, or by calling 311.