California is cooking — and there’s no real relief in sight.

A brutal heat wave is expected to grip huge swaths of the state through next week, with forecasters warning the oppressive conditions could linger well into October.

The National Weather Service issued heat advisories stretching from Southern California through Central California and into the Bay Area beginning Friday, with triple-digit temperatures expected across inland communities.

Parts of the San Fernando, Simi, Santa Clarita, San Gabriel, Antelope, Apple, Lucerne, Moreno and Coachella valleys could feel as hot as 107 to 111 degrees when factoring in the heat index, according to meteorologist Jason Farhang.

Actual daytime temperatures in those areas could reach 102 to 106 degrees.

Coastal communities and mountain areas from Ventura to San Diego are expected to see temperatures between 90 and 98 degrees, putting millions of residents in areas that typically escape the worst of California’s heat under unusual stress.

“The coastal zones and mountains are extremely hot with a temperature range of 90°F to 98°F This puts a lot more folks under more significant heat stress than normal in large populations from Ventura to San Diego counties,” Farhang wrote.

The heat is also expected to bake parts of the East Bay and San Francisco Bay shoreline, Western Sonoma County Hills, the Santa Cruz Mountains, Monterey County, North Bay Interior Mountains and portions of the Southern Salinas Valley.

Some of those areas could top 100 degrees, with little relief after the sun goes down.

“Long duration heatwave expected Friday through early next week in California. Minimum temperatures in the low to mid 70s will provide little to no overnight relief to those without adequate cooling or hydration,” the National Weather Service said.

“Extreme heat warnings are in effect for parts of Southern California and Heat advisories are in effect for much of Central California.”

“This is one of the longer-duration ones that I’ve seen in my time at this office,” NWS meteorologist Rose Schoenfeld told the Los Angeles Times. Schoenfeld, who has worked at the Oxnard office since 2023, said the heat could last until the middle of the month.

The unusual stretch is being linked in part to a strong El Niño pattern and above-normal sea surface temperatures.

Officials are urging Californians to take the heat seriously, particularly people without reliable air conditioning or access to water.

“Drink water, and if possible, take water to those who are vulnerable. Take extra precautions when outside. Wear lightweight and loose fitting clothing.”

“Try to limit strenuous activities to the early morning or evening. Take action when you experience symptoms of heat exhaustion and/or heat stroke,” the warning added.

Residents should also check on elderly relatives and neighbors during the prolonged heat.