An excessive heat warning was extended to 9 p.m. Thursday for the San Fernando, Santa Clarita, San Gabriel and Antelope valleys, as well as the San Gabriel and Santa Monica mountains.By CBSLA Staff

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LOS ANGELES (CBSLA) – Tuesday saw some of the hottest triple-digit temperatures of the week as the heat wave which has gripped the Southland continues, bringing with it the risk of rolling blackouts, thunderstorms and more wildfires.

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An small plane is seen flying above power lines in Long Beach, Calif. on Aug. 16, 2020. (Getty Images)

An excessive heat warning was extended to 9 p.m. Thursday for the San Fernando, Santa Clarita, San Gabriel and Antelope valleys, as well as the San Gabriel and Santa Monica mountains.

The National Weather Service said conditions in those areas would be “dangerously hot.”

The scorching temperatures made it tough on residents and businesses, especially restaurants — which are currently forced to serve customers outside due to the coronavirus pandemic.

“With the mask, it makes everything worse,” said Jinah Park, owner of Village Pizzeria in Sierra Madre. “It’s really horrible.”

No one sat on the patio tonight, but delivery orders continued to come in — making for a sweltering situation inside.

“Three ovens running right now, and the air conditioning can not cool everything with all the heat coming from the back,” Park said.

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.

It marked another busy day for Daniel Bushay, who owns an A/C business. He said he had eight calls from people asking for help fixing their air conditioning units. Wednesday, he has 10 more appointments.

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“I normally stress to people on days like this, set it at 78,” he said. “If it can’t get down below that, it won’t get any cooler.”

The sign posted outside an ice cream shop in Sierra Madre, explaining why they would not be open Tuesday. (CBSLA)

The heat wave is being caused by a strong ridge of high pressure anchored over Nevada, forecasters said.

The NWS reported record high temperatures for an August 17 in Lancaster, which reached 110 degrees, and Palmdale, which reached 111.

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 from 3 p.m. through 10 p.m. through Wednesday.

The California Independent System Operator — which oversees roughly 80% of the state’s power grid through Southern California Edison, Pacific Gas and Electric Company and San Diego Gas & Electric – said the state avoided rolling blackouts Monday due to conservation efforts and cooler temperatures.

California Gov. Gavin Newsom warned at a news conference Monday afternoon that rolling blackouts through Thursday were “very likely.”

The L.A. Department of Water and power was not expected to be impacted by the outages since the utility is locally-owned and runs its own plants. It will help supply 900 megawatts of power to the state grid Tuesday.

The L.A. County Department of Public Health also reported Tuesday that the Santa Clarita, East San Gabriel and Pomona-Walnut valleys, along with the San Gabriel Mountains, were experiencing unhealthy air quality due to the smoke from the Lake and Ranch 2 fires. Some neighborhoods were seeing soot and ash.

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(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)