The warning turned into an outage on Friday. PG&E switched off electricity to 395 customers in unincorporated Alameda County just east of Livermore at 3:25 p.m. Oct. 9, according to Patch, citing the utility's outage center.

The affected area runs around Interstate 580, Patterson Pass Road and Altamont Pass Road. PG&E told customers there that power was turned off because of high winds and dry conditions, and that crews will inspect lines and equipment for damage once the weather improves before turning the lights back on. Patch reported the elevated fire conditions are expected to last until Monday.

How we got here

Earlier Friday, NBC Bay Area reported that PG&E had warned 386 customers in the rural hills south of the Altamont Pass, along with a handful of customers in rural Napa County, that they could lose power starting in the afternoon. The station said temperatures in Livermore were expected to climb above 80 degrees, and that restoration might not come until around noon Sunday.

PG&E calls these cuts Public Safety Power Shutoffs. The goal is to keep energized lines from swinging in the wind and sparking a fire.

The bigger picture

In a 3 p.m. update, PG&E said it had expanded the shutoff to customers in Alameda, Merced and San Joaquin counties. That came after the utility began cutting power in targeted parts of Fresno, Kern, Kings, San Benito and San Luis Obispo counties at about 1 p.m. In total, PG&E said, the event could affect about 12,200 customers in 17 counties and three tribal areas through Monday.

According to KCRA, PG&E's schedule lists Alameda County under a watch or warning on Oct. 9, 10 and 11, but not Oct. 12. Napa and Solano counties stay on the list through Monday. The utility's meteorologists flagged dry, gusty northwesterly winds over higher terrain Friday and another round of dry northerly winds in the western Sacramento Valley on Sunday.

What to do

PG&E says customers can check whether their address is being monitored or has been shut off at pge.com/pspsupdates. The utility sent notices by text, email and automated phone calls on Thursday, Oct. 8.