UPDATE, Oct. 9, 6:36 p.m.: With strong winds yet to kick up as of Wednesday evening, PG&E was able to restore power to 44,000 customers in the North Bay and Sierra foothills. The utility said it was still monitoring weather conditions for the East Bay and South Bay and hadn't yet decided the timing of shut-offs in those areas. Read the latest here.

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PG&E is preparing to start the second phase of a power shut-off to mitigate wildfire risk, adding to the growing number of San Francisco Bay Area customers who will soon be in the dark.

PG&E shared on Twitter at 12:29 p.m. that proactive shutoffs for Bay Area customers will begin later this afternoon and into early evening in portions of Alameda, Contra Costa, San Mateo and Santa Clara counties, including parts of big cities like Oakland and San Jose. Originally, shuts-offs were projected to start around noon.

Phase one of the preventative shutdown was completed at 4 a.m. Wednesday, impacting nearly 150,000 Bay Area customers. (That's approximately 450,000 residents when you consider about three people live in each household on average.)

As of 5:30 a.m., Solano County had 31,632 customers without power, Napa County 32,780, Sonoma County 67,289 and Marin County 10,202, according to KTVU-TV.

In response to dry, windy conditions, the utility is cutting power throughout the state and projects 800,000 northern and central California customers in 34 counties will be impacted.

Phase one de-energized approximately 513,000 California PG&E customers. Phase 2 is expected to affect 234,000 more customers.

The blue areas on this map show where PG&E has planned outages for Wednesday, Oct. 9, 2019.

A third phase is under consideration and while specific locations are still to be determined, it's unlikely to impact more Bay Area residents.

The PG&E official site is currently "experiencing a high volume of traffic" and is intermittently crashing or not loading at all. If you're looking for an interactive map of power shut-off areas, we have a map here.

PG&E confirmed that it has implemented the first phase of a Public Safety Power Shutoff (PSPS) across significant portions of its service area in response to a widespread, severe wind event.

The shut-off comes as dry and windy weather is forecast for the Bay Area, with gusts up to 50 mph Wednesday. The National Weather Service called the wildfire danger "extreme" and the event may bring the strongest offshore winds since the October 2017 North Bay fires.

The National Weather Service has a Red Flag Warning in effect for the North Bay mountains and valleys and the East Bay hills and valleys Wednesday 5 a.m. to Thursday 5 p.m. A warning is also in place for the Santa Cruz Mountains Wednesday 5 p.m. to Thursday at noon.

PG&E wildfire safety expert Sumeet Singh said Tuesday night in a press conference that the company's decision to cut electricity to customers in 34 Northern and Central California counties is "a last resort" in the face of an unprecedented and sweeping wildfire risk from the hot, dry weather and gusty winds.

Gov. Gavin Newsom earlier said residents should be outraged by the largest preventive outage in state history.

The utility says some customers could be without power for five days because every inch of power line must be inspected and declared safe before electricity is restored.

The number of potential customers affected in each Bay Area county, according to PG&E, is:

  • 32,613 customers in Alameda County
  • 40,219 customers in Contra Costa County
  • 66,289 customers in Sonoma County
  • 32,124 customers in Napa County
  • 14,766 customers in San Mateo County
  • 38,123 customers in Santa Clara County
  • 32,862 customers in Solano County
  • 9,855 customers in Marin County

San Francisco County is not expected to be affected.

FULL PG&E SHUTOFF COVERAGE:

- Map shows Bay Area neighborhoods that will be without power

- PG&E map down? Here's an interactive NorCal power shutoff map that actually works

- Essentials to buy for PG&E's planned power outage

- Here's what you should (and shouldn't) do during a power outage

- When will my power turn off?

- Cal, Bay Area schools announce canceled classes, closure

- UPDATE: 2 Bay Area tunnels expected to remain open

Amy Graff is a digital editor at SFGATE. Email: agraff@sfgate.com.

The Associated Press contributed to this report. SFGATE Digital Editors Dianne de Guzman and Alix Martichoux contributed to this report.