SAN FRANCISCO (KRON) — Triple-digit temperatures on Wednesday are expected to cause strain to California’s power grid.

Cal ISO issued a Flex Alert from 4 p.m. to 9 p.m. in anticipation of Californians cranking up the air conditioning and plugging in fans due to the excessive heat.

It’s voluntary to participate, but Cal ISO says energy conservation will be essential.

“Conserving electricity during the late afternoon and early evening is crucial because that is when the grid is most stressed due to higher demand and declining solar energy production,” Cal ISO says.

On Wednesday afternoon, officials announced that the Flex Alert will be extending through Thursday as the heat continues. The alert will be in effect from 4 p.m. to 9 p.m.

Flex Alerts have helped prevent emergency measures like rotating power outages.

People are asked to avoid using appliances like laundry machines and dishwashers during the hours the Flex Alert is in effect. That means you can take care of those chores before 4 p.m. or after 9 p.m. without concern. Other actions you can take are lowering thermostats to 78 degrees or higher, and turning off unnecessary lights.