San Diego utility customers: Be ready for a Flex Alert this week

An incoming heat wave may strain the electric grid in California and across the West.
An incoming heat wave may strain the electric grid in California and across the West.
(Rob Nikolewski/The San Diego Union-Tribune)

Hot weather across the West has California’s grid operator on the alert


An anticipated heat wave across the West may lead the California Independent System Operator to issue the first Flex Alert of the year — a request for utility customers to reduce their electricity use during the late afternoon and early evening hours.

Forecasters see hot weather descending on the interior areas of Northern California, across the desert Southwest and up into the Pacific Northwest through Wednesday, which could strain the power systems for California and neighboring states.

“Widespread heat waves can cause energy supply shortages, as resources are stretched thin across multiple states,” the system operator said in a heat bulletin released Sunday. “As part of an interconnected Western grid, the California ISO is preparing for tight conditions and taking coordinated steps with its neighbors to ensure adequate power supply during this week’s hot weather.”

When extremely hot weather spreads over multiple states in the West, grid managers sometimes struggle to allocate the resources needed to keep the electric grid balanced as millions of customers crank up their air conditioners.

The California ISO said it believed there are sufficient resources to meet California’s demand but “if weather or grid conditions worsen,” grid managers may issue emergency notifications to try to access additional megawatts of electricity.

To make sure all generators and transmission lines are available during the heat wave, the Cal ISO has already sent notices to utilities and transmission operators, calling on them to avoid taking grid assets offline for routine maintenance on Tuesday, Wednesday and Thursday.

If things get tighter, the California ISO may issue a Flex Alert and ask for customers across the state to voluntarily cut energy consumption — usually from 4 p.m. to 9 p.m.

The California ISO manages the electric grid for about 80 percent of the state and a small portion of Nevada.

An intense heat wave in late August and early September 2022 that blanketed the West led the system operator to issue Flex Alerts for a record 10 consecutive days.

It appears San Diego will avoid the worst effects of the rise in temperatures forecast for this week.

Winds gathering from Hurricane Fernanda, churning southwest of the Baja California Peninsula, is expected to keep San Diego County from experiencing dangerous levels of heat for the coming days.

But temperatures in Northern California’s inland areas and the desert Southwest are forecast to be 5 to 15 degrees above normal. And through Wednesday, the Pacific Northwest is preparing for temperatures 10 to 25 degrees warmer than average for this time of year.

U-T staff writer Gary Robbins contributed to this story.