Grid operator, expecting hot weather and high demand for electricity, issues flex alert for Wednesday

State officials, anticipating high temperatures and an attendant rise in demand for electricity, issued a flex alert from 4 to 9 p.m. Wednesday.

The California Independent System Operator, a public benefit corporation that manages the power grid that provides energy to about 80% of the state, called on households to voluntarily restrict their energy use Wednesday afternoon and evening.

Temperatures are expected to rise in parts of Northern California, which will probably cause an increase in electricity use from air conditioning and strain the power grid, the operator said in a statement.

The grid comes under most stress in the late afternoon and early evening, when demand is highest and the production of solar energy tapers off. The grid operator asked that customers on Wednesday turn off unneeded lights, not use major appliances until after 9 p.m. and set thermostats to 78 degrees or higher, if safe.

Temperatures in Los Angeles climbed Tuesday, a day after rain fell in record-setting levels. The National Weather Service predicted a high of 87 degrees in Los Angeles County on Wednesday, with patchy fog yielding to clear skies in the morning. Temperatures are expected to hover in the mid- to high 80s through the week.