The National Weather Service warned Tuesday that excessive heat and a heightened risk of wildfires would last at least through Thursday, and Orange County temperatures are expected to reach triple-digit territory for the first time since the event began.
An excessive heat warning, which has been extended since it was first issued last week, will be in force until 9 p.m. Thursday in the San Fernando, Santa Clarita, San Gabriel and Antelope valleys, as well as the San Gabriel and Santa Monica mountains. The weather service said conditions in those areas would be “dangerously hot.” In inland Orange County and the Santa Ana Mountains, the warning will expire at 10 p.m. Thursday.
A less serious heat advisory will be in effect until 9 p.m. Thursday in the L.A. coastal zone — beach cities, metropolitan Los Angeles, Downtown L.A. and the Hollywood Hills.
“Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities,” according to he NWS. “Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening.”
The NWS noted that some coastal areas on Monday saw significantly decreased temperatures — “in some cases by as much as 15-20 degrees” — in the morning and early afternoon hours thanks to lingering low clouds. But that relief wasn’t expected to last, with Tuesday expected to produce sweltering temperatures once again.
“Very hot conditions will continue through the week with very warm nights, especially for valley and interior areas,” according to the NWS. “Temperatures will cool only slightly later in the week and will remain above normal through early next week. There is a slight chance of thunderstorms through Wednesday mostly over the mountains and the Antelope Valley.”
The heat wave is the fourth to attack the region this summer as well as the longest and fiercest. It is caused by a strong ridge of high pressure anchored over Nevada, forecasters said.
“The high does start to weaken Wednesday and Thursday but not significantly enough to provide all that much relief,” according to the NWS. “It will likely take until Friday or perhaps not until Saturday before high temps drop below advisory/warning levels.”
In Orange County, where temperatures had been staying lower than those in L.A. County, some communities are forecast to reach the low 100s Tuesday. Several other locales will be in the high 90s.
Monday afternoon, the NWS reported temperature record highs for an August 17 in Lancaster, which reached 110 degrees, and Palmdale, which reached 111.
Along with torrid weather, the NWS forecast “elevated fire danger.” The NWS has not issued any red flag warnings because winds have not been strong enough to meet NWS criteria, according to forecasters.
The excessive heat has led to stress on the state’s electrical grid over recent days, prompting some rolling blackouts Friday night. Utility companies warned customers that more such power interruptions are possible in peak afternoon hours during the heat wave. Flex Alerts urging customers across the state to conserve energy will be in effect each afternoon and evening through Wednesday.
The NWS forecast partly cloudy skies in areas of L.A. County nearest the coast Tuesday and sunny skies in valley locations, along with highs of 86 at LAX; 87 in Avalon; 94 in Long Beach; 96 in Downtown L.A. and on Mount Wilson; 99 in San Gabriel; 102 in Pasadena; 103 in Burbank; 107 in Saugus; 109 in Woodland Hills; and 111 in Palmdale and Lancaster. Hot, above-average temperatures will persist until next week.
Sunny skies were forecast throughout Orange County Tuesday, along with highs of 82 in San Clemente; 83 in Newport Beach; 84 in Laguna Beach; 91 on Santiago Peak; 97 on Ortega Highway at 2,600 feet and in Irvine; 98 at Fremont Canyon; 99 n Fullerton; and 101 in Anaheim, Mission Viejo and at Trabuco Canyon. Temperatures will decrease by a few degrees Wednesday and remain in the high 80s and low 90s several days.
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