A Flex Alert advisory message shows on a message board on Interstate 710 in July 2021 in Long Beach, California.
CNN  — 

With temperatures in parts of California expected to exceed 100 degrees Wednesday, Golden State residents are being asked to conserve electricity to ensure the power grid isn’t pushed over the edge.

The manager of 80% of the state’s power grid – the California Independent System Operator – issued a statewide Flex Alert asking residents to minimize electricity use from 4 to 9 p.m. Wednesday.

The alert – the first issued this year – comes as the western US grapples with drought conditions intensified by the effects of the climate crisis.

During the alert window, the operator recommends residents set their thermostats to 78 or higher if health permits; avoid using major appliances; and turn off unnecessary lights.

That’s because air conditioner use typically increases demand as temperatures rise, and supply especially tightens in the evening as solar energy supplements decline. So the operator says it wants residents to use less electricity than usual Wednesday evening to avoid straining the grid, which could lead to outages.

Heat advisories from the National Weather Service are in effect across parts of California – mostly in the interior portions of the state, from as far south as the Bakersfield area stretching north to near the California-Oregon line – with some remaining in place through Friday.

High temperatures Wednesday could reach 108 degrees in Redding; 106 in Fresno and Bakersfield; and 103 in Sacramento, the weather service said.

Parts of interior central and northern California are under a high heat risk Wednesday – the third highest of four levels, according to the weather service. That means a high risk of heat-related illness to much of the population without effective cooling or adequate hydration, the service says.

Areas along the coast are expected to be cooler: High temperatures in the low 70s are expected for San Francisco; the high 70s or low 80s for Los Angeles; and the low 80s for San Diego, the weather service said.

The California Independent System Operator recommends residents prepare for the power conservation window by cooling their homes before 4 p.m. by setting thermostats as low as 72 degrees. It also recommends meal preparation requiring ovens and stoves be done before 4 p.m., along with adjusting blinds and drapes to cover windows.

Sweltering heat also is expected in the Northwest through Friday. Portland, Oregon, is expected to reach a high of 100 degrees Wednesday, and Yakima, Washington, could reach around 102, the weather service said.

The high heat in the West comes as the region also deals with drought.

As of last week, all of California was under various drought intensities, with more than 45% of it experiencing two of the most extreme drought categories, according to the US Drought Monitor.

The severe drought has been draining the nation’s largest reservoirs – Lake Mead in Nevada and Arizona, and Lake Powell in Utah and Arizona – as the Colorado River dries up.

On Tuesday, the federal government announced the Colorado River will operate in a Tier 2 shortage condition for the first time starting in January. That means Arizona, Nevada and Mexico will have to further reduce their Colorado River use. California will not yet see cuts made to the water it gets from the river.

CNN’s Taylor Romine, Ella Nilsen and Rachel Ramirez contributed to this report.