FOLSOM (AP) – California’s power grid operator called for voluntary conservation of electricity Thursday as high heat gripped the state.

The California Independent System Operator issued a Flex Alert for the period from 3 p.m. to 10 p.m. due to an expected increase in electricity demand, primarily from use of air conditioning.

READ MORE: Auburn Wildlife Rescue Receives First Wildfire Burn Victim Of Year

READ MORE: Inmate Walks Away From Conservation Camp In El Dorado County, CDCR Says

Late afternoon and early evening is when the grid is most stressed and solar power production falls.

The heat is being produced by a ridge of high pressure covering the entire West and extending into Alaska, the National Weather Service said.

In mid-August, a heat wave strained the grid to the point that the operator ordered utilities to implement rolling blackouts.

MORE NEWS: Big Rig Crash Causes Major Backups On I-80 In Colfax

Copyright 2020 The Associated Press.