It’s hot, humid and smoky

Hot weather continued to scorch Southern California on Friday, with firefighters battling brush fires, businesses reporting runs on cold treats and air conditioners and everyone bracing for a few more days of sauna-like weather.

Firefighters were able to contain or gain ground on three large fires caused by lightning strikes earlier in the week in Riverside County, even as temperatures crested above 105 degrees there.

And in Los Angeles County, where lightning sparked 11 small fires Thursday in the Antelope Valley, Los Angeles County Fire Inspector Don Kunitomi said all were contained. A small brush fire in Santa Clarita was also quickly extinguished.

The National Weather Service extended an excessive heat warning for valley and mountain areas in Los Angeles County, where temperatures are expected to range from 95 to 110, until 9 p.m. Saturday. Officials warned the public to drink plenty of water and to refrain from leaving children, pets or the elderly in cars.

Officials also encouraged people to seek air-conditioned shelters in public libraries, senior centers and recreational facilities.

In the San Fernando Valley, where temperatures hit 104, selected centers will remain open from 10 a.m. to 9 p.m. on Saturday and from noon to 9 p.m. on Sunday. The locations include recreational and senior centers in Canoga Park, North Hollywood, Panorama City, Sunland, Sylmar, Sherman Oaks and Northridge.

“Because of the dangerously warm temperatures, people should be cautious to drink liquids and check on their neighbors,” said Bonnie Bartling of the National Weather Service.

Bartling said temperatures are expected to begin dropping Sunday and return to normal by Wednesday, as the high-pressure system causing the heat wave leaves the area.

State officials are investigating the possible heat-related death Wednesday of a Central Valley farmworker. The state’s Division of Occupational Safety and Health said the 54-year-old collapsed in a vineyard in Arvin, where temperatures reached into the high 90s, as he was reportedly helping load heavy boxes of grapes onto trucks.

He was taken to Kern Medical Center, where he was pronounced dead around 4:30 p.m. He was the fifth worker to die this summer from potentially heat-related causes, according to Cal-OSHA.

Meanwhile, residents in the tiny desert community of Sage in Riverside County who had been evacuated were able to return to their homes after a brush fire that had burned 80 acres was fully contained.

Firefighters continued to battle a larger fire near Lake Skinner that was only 30% contained Friday evening. The Cactus fire blackened 647 acres and firefighters were using air tankers and helicopters to slow the spreading flames. An evacuation center opened at Hemet High School.

Another wildfire in a sparsely populated area east of Murrieta in the southwest corner of the county burned 503 acres and was 60% contained by Friday evening, according to the Riverside County Fire Department. Nearly 230 firefighters and three water-dropping helicopters were called in to battle that blaze, called the Skinner fire.

Chatsworth recorded Southern California’s highest daily temperature Friday, 104. There, Caitlin Chapman, a server at Baskin-Robbins on Devonshire Street, said that the heat wave had doubled the number of customers Friday and that refreshing Rainbow Sherbet and Wild and Reckless — another fruit sherbet — were the day’s flavors of choice.

A nearby hardware store reported runs on air conditioners, fans, patio misters and shade cloths for plants sensitive to heat.

“We’ve sold more of this stuff in the last few days than we have in the last month,” said a store employee, who declined to give his name. “Pretty soon we’re going to get low energy surges in the valley.”

So far, however, the Department of Water and Power is reporting no unusual demand for electricity. To conserve energy, officials advised the public to adjust thermostats to 78 degrees, avoid cooking and using appliances during peak heat hours, turn off lights and ventilate homes by opening windows at night.

Temperatures reached 95 in downtown Los Angeles, 103 in Pomona, 103 in Lancaster and 96 in Anaheim. Along the coast, Malibu reported 66 and Redondo Beach, 75. In Ventura County, temperatures ranged from 76 in Ventura to 103 in Ojai.

teresa.watanabe@latimes.com

Phil Willon contributed to this report.