A public safety power shutoff event by PG&E will black out nearly 800,000 customers across 34 Northern California counties starting Wednesday, the utility confirmed in a news release Tuesday afternoon.
Originally estimating Monday a total of 650,000 customers, PG&E said Tuesday that about 150,000 additional customers will be affected in parts of Humboldt, Kern, Marin and Trinity counties.
The utility said with certainty at a 7 p.m. news conference that about 500,000 customers across the north state would be plunged into an engineered blackout between midnight and 4 a.m.
“This is the measure of last resort,” Sumeet Singh, PG&E’s vice president of the community wildfire safety program, told reporters late Tuesday.
Blackouts are still planned for the balance of the original 30 counties clustered around the Central Valley and Central Coast before 4 a.m. Those counties are: Alpine, Amador, Calaveras, Colusa, Glenn, Lake, Mariposa, Mendocino, Plumas, San Joaquin, Santa Barbara, Santa Clara, Santa Cruz, Shasta, Sierra, Stanislaus, Tehama, Tuolumne and Yolo.
Bay Area counties – such as Alameda, Contra Costa, San Mateo, Santa Clara and Santa Cruz — were expected to go offline later in the day.
A map showing a rough outline of possible outage areas was also provided by PG&E, last updated Monday afternoon.
PG&E’s statement lists cities and unincorporated towns in each county that may be partially impacted, and gives an estimated number of outages for each county, but does not predict how many customers or in which portions of each city the blackouts are being considered.
Some counties, such as San Joaquin and Santa Barbara, are projected for just a few dozen outages.
Others, including Sonoma, Placer and El Dorado counties, are estimated to have more than 50,000 customers lose power in the event of a shutoff.
Populous cities that could see at least some customers lose power include Oakland, San Jose, Chico, Napa, Grass Valley, Roseville, Rocklin, Lincoln and Redding.
Regions devastated by wildfires in the last two years, including Santa Rosa, Paradise, Magalia and much of wine country, are also included in PG&E’s latest estimate.