LOS ANGELES — California faces a heat wave Friday that could bring dangerously high temperatures throughout the state, increased wildfire danger and a higher threat of the spreading of the coronavirus as people flock to lakes, beaches and other recreation areas.

High pressure building over Western states will push temperatures into triple digits in many places through the weekend and sweltering weather could continue into next week.

Temperatures in Fresno could hit 111 degrees by next week. Palm Springs and other desert regions could approach 120 degrees and even cooler areas, such as coastal regions and portions of San Francisco, could reach 80 degrees, the National Weather Service predicted.

“Dangerously hot conditions will occur during the afternoon and early evening hours each day,” a National Weather Service warning said.

Excessive heat watches and warnings were issued up and down the state, with forecasters warning that even nighttime temperatures would remain toasty.

Los Angeles planned to open cooling centers, but with limited capacity because of coronavirus social distancing requirements.

The California Independent System Operator, which manages the state’s power grid, issued a statewide Flex Alert for Friday, calling for voluntary electricity conservation from 3 p.m. to 10 p.m. when there’s expected to be higher demand, mainly from the use of air conditioners.

The Scorching Temperatures Are a Concern for Firefighters Battling Blazes

In addition, cloudy remnants of a tropical weather system will reduce solar generating power and lead to tighter energy supplies, operators said.

People were asked to turn off unnecessary lights and avoid using major appliances such as washing machines during those hours.

The scorching temperatures are a concern for firefighters battling blazes that have destroyed several homes and have erupted near both rural and urban foothill neighborhoods, driving through tinder-dry brush.

Temperatures were expected to top 100 degrees Friday at Lake Hughes, near a wildfire that has burned at least three buildings, including some homes, and remained out of control after tearing through chaparral and dense forest in the Angeles National Forest.

The blaze was fueled by the dry vegetation.

“This will be a major fire for several days,” said Chief Robert Garcia with the U.S. Forest Service.

In addition to the possibility of heat stroke and other hot-weather illnesses, health officers were concerned that people will pack lakes, beaches and other recreation areas without following mask and social distancing orders — a major concern in a state that has seen more than 590,000 coronavirus cases and nearly 11,000 deaths.

Israel saw a COVID-19 resurgence after a May heat wave inspired school officials to let children remove their masks, Dr. George Rutherford, an epidemiologist at the University of California, San Francisco, told the San Francisco Chronicle.

“People will want to take off their masks when it’s hot,” Rutherford said. “Don’t do it.”

On Thursday, some people gathering at Lake Merritt in Oakland weren’t worried, though.

Brenda Jackson, who was picnicking with her husband, said she wasn’t afraid of contracting COVID-19.

“Everybody’s been really smart, social distancing and wearing masks,” she told the Chronicle.