By CBSLA Staff

LOS ANGELES (CBSLA) The California Independent System Operator has issued another statewide Flex Alert for Monday, urging residents to conserve energy between the hours of 4 p.m. and 9 p.m.

U.S. Park Ranger Jeannette Jurado takes a surface temperature reading from an unofficial thermometer reading 132 degrees Fahrenheit at Furnace Creek Visitor Center on July 11, 2021 in Death Valley National Park, Calif. (Getty Images)

This marks the third Flex Alert in the last four days. Cal ISO, the independent, nonprofit agency that oversees the state’s power grid, issues a Flex Alert when high power use threatens to put stress on the state’s grid.

The strain on the grid is stemming from a combination of extreme heat in several parts of the state and a growing wildfire in Southern Oregon that has damaged transmission lines used to supply power to California.

During a Flex Alert, people are asked to keep their air conditioning thermostats no lower than 78 degrees and limiting the use of major appliances, such as washing machines and dishwashers. They should also turn off lights and unplug cell phone chargers when not in use.

The Bootleg Fire burning in the Fremont-Winema National Forest in Southern Oregon has scorched more than 146,000 acres. The blaze continues to pose a threat to Path 66 — a vital electric line corridor linking the California power grid to suppliers in the Pacific Northwest, according to CBS San Francisco.

“Transmission lines, knocked out by the Bootleg Fire in Oregon, are still out of service, reducing power supplies by as much as 5,500 megawatts typically imported into California and other balancing authorities south of Oregon,” Cal ISO tweeted Sunday. 

Last year, heat waves sparked rolling blackouts in California for the first time since 2001, and helped contribute to the spread of a historic number of wildfires up and down the state which destroyed thousands of homes and forced tens of thousands of people to evacuate.

Meanwhile, temperatures are expected to soar Friday in the Antelope Valley. An excessive heat warning is in place until 9 p.m. for the cities of Palmdale and Lancaster, which could hit a high of 110 degrees.

A heat advisory is also in place through 9 p.m. for the Los Angeles County mountains, excluding the Santa Monica mountains, with temperatures in those areas reaching 107 degrees.

Residents are encouraged to keep an eye out for heat-related illnesses in themselves and others. Symptoms of heat stroke — which is a medical emergency — include feeling hot and confused and a decrease in level of consciousness. Call 911 if this occurs.

Heat exhaustion can happen when people exert themselves in extreme heat and feel lightheaded, dehydrated and perhaps fainting.

People most vulnerable include the very young, elderly and those with certain health conditions. Still, everyone is urged to take precautions and check on neighbors who are most vulnerable.

Temperatures are expected to cool slightly by mid-week as a high-pressure system that is over the region moves east, according to CBSLA Meteorologist Amber Lee.