The Latest on power outages in California (all times local):

7:40 a.m.

Pacific Gas & Electric has begun shutting off power to people in the San Francisco Bay Area and portions of California’s northern coast amid warm and windy weather that can help fan wildfires. The utility is trying to prevent its power lines from sparking fires.

Grass Valley's Dionicio Torres looks at the gas can selection before taking the last 5-gallon gas can on the shelves at B&C Ace Home & Garden Center, in Grass Valley, Calif., Tuesday, Nov. 19, 2019, in preparation of Wednesday's planned public safety power shutdown. (Elias FunezThe Union via AP)

Grass Valley's Dionicio Torres looks at the gas can selection before taking the last 5-gallon gas can on the shelves at B&C Ace Home & Garden Center, in Grass Valley, Calif., Tuesday, Nov. 19, 2019, in preparation of Wednesday's planned public safety power shutdown. (Elias FunezThe Union via AP)

PG&E spokeswoman Katie Allen says some people in the wine country counties of Napa and Sonoma lost electricity at about 7 a.m. Power has also been cut in parts of Mendocino and Yolo counties.

No details were immediately provided as to how many people lost electricity, but the shut-offs are expected to affect 375,000 people and last into Thursday.

Officials in some counties say schools, libraries and other public buildings will be closed Wednesday because of the outages.

A shopper looks at extension cords at B&C Ace hardware store, Tuesday, Nov. 19, 2019, in Grass Valley, Calif., in preparation of the planned Pacific Gas & Electric power shutdown scheduled for Wednesday and Thursday. (Elias FunezThe Union via AP)

A shopper looks at extension cords at B&C Ace hardware store, Tuesday, Nov. 19, 2019, in Grass Valley, Calif., in preparation of the planned Pacific Gas & Electric power shutdown scheduled for Wednesday and Thursday. (Elias FunezThe Union via AP)

It’s the latest in a series of mass, planned outages prompted by extreme fire risk weather conditions over the past two months.

12:00 a.m.

Pacific Gas & Electric is once again shutting off power to large areas of central and Northern California because of fire danger.

Extension cords of all gauges and lengths stock the shelves at B&C Ace hardware, Tuesday, Nov. 19, 2019, in Grass Valley, Calif., in anticipation of the next public safety power shutdowns. (Elias FunezThe Union via AP)

Extension cords of all gauges and lengths stock the shelves at B&C Ace hardware, Tuesday, Nov. 19, 2019, in Grass Valley, Calif., in anticipation of the next public safety power shutdowns. (Elias FunezThe Union via AP)

PG&E planned blackouts Wednesday in parts of 18 counties ranging from north of Sacramento to the northern San Francisco Bay Area, wine country and the Sierra Nevada foothills.

The shut-offs could affect about 375,000 people and could last into Thursday.

It’s the latest in a series of mass outages prompted by weather conditions in the past two months. Brush is bone-dry from a lack of fall rains. PG&E is worried that gusts might fling debris into its power lines, sparking catastrophic wildfires.

The previous outages included one that affected 2.5 million people last month, inconveniencing and outraging customers. But PG&E says it’s a matter of public safety.