LOS ANGELES - More triple-digit weather will bake parts of the Southland into the weekend, with the Antelope Valley and Santa Clarita Valley likely to bear the brunt of the high-pressure system and the state urging energy conservation to prevent outages.
An excessive heat warning will be in effect in the Antelope Valley through 9 p.m. Monday, with the National Weather Service predicting "dangerously hot conditions with temperatures up to 113 expected."
Forecasters said temperatures won't drop dramatically overnight in the area, with lows expected in the mid-70s to mid-80s.
"Strong upper level high pressure will bring excessively hot temperatures to the interior valleys, mountains and deserts through early next week, with above normal temperatures most everywhere away from the coast," according to the NWS.
Forecasters said the excessive heat warning could potentially be extended to the Santa Clarita Valley on Friday and beyond, depending on how the high-pressure system unfolds. For the time being, the NWS issued a less severe heat advisory for the Santa Clarita Valley that will be in effect from 10 a.m. Friday until 9 p.m. Sunday, with temperatures up to 105 degrees expected.
A heat advisory will be in effect from 10 a.m. Friday to 9 p.m. Monday for Los Angeles County mountains, excluding the Santa Monica range. Forecasters said lower elevations could see temperatures of up to 106 degrees.
A continuing onshore flow will keep temperatures cooler along the coast.
Meanwhile, the California Independent System Operator, which manages the state's power grid, has declared a Flex Alert -- a call for voluntary conservation in hopes of reducing strain on the system and preventing outages – that will be in effect from 4 to 9 p.m. Friday. Cal ISO has also issued a statewide grid warning notice due to loss of resources and fire threat to the transmission system and is encouraging conservation. They are also forecasting a resources deficiency with all available resources in use or forecasted to be in use.
Cal-ISO officials urged residents to set their thermostats to 78 degrees or higher during the alert, avoid using major appliances and turn off all unnecessary lights. Residents should also consider pre-cooling their homes before the alert takes effect and use window coverings to keep rooms cool.
While the weather is expected to be hot, forecasters said temperatures will likely remain just shy of daily-record levels, which are in the 110-115 range, and "certainly short of all-time records which are in the 113-117 range."
The high-pressure system is expected to weaken early next week, but it will still be warmer than usual. Triple-digit temperatures are expected throughout next week in the Antelope Valley.
As with other heat events, the NWS advised residents in the Antelope Valley to stay hydrated, avoid the sun when possible and check up on relatives and neighbors who might be susceptible to heat illness.
"Take extra precautions if you work or spend time outside," forecasters advised. "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 Los Angeles County Department of Public Health issued an extreme heat warning that will be in effect from Friday through Tuesday in the Antelope Valley, from Friday through Monday in the Santa Clarita Valley and Saturday through Monday in the western San Fernando Valley.
A county heat alert will be in effect Saturday and Sunday in the western San Gabriel Valley and eastern San Fernando Valley.
County officials said residents without air conditioning at home can take advantage of cooling centers, with information on locations available at https://ready.lacounty.gov/heat/ or by calling 211.
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