The second phase begins around 12 p.m. on Wednesday afternoon.
PG&E said the severe weather incident prompting its precautionary shutoffs - hot, dry conditions and winds gusting at up to 110 kph - was expected to last through mid-day Thursday in northern and central California.
The company apologized for the outage in a tweet, said it was working to fix the problem, and urged clients in another post to sign up for alerts via text message.
Northern California's largest utility provider confirmed Tuesday afternoon that it will "proactively" turn off power for almost 800,000 customers-including an unknown number in Morgan Hill-as a forecast of high winds moves onto the coast.
A power company is cutting electricity to around 800,000 homes, businesses and other locations in Northern California, in an attempt to prevent wildfires.
While many East Coast residents have learned to cope with power outages from hurricanes, weather-related outages are a relatively new phenomenon in California.
Before PG&E Corp.'s massive blackout swept across Northern California, Tesla Inc. issued a politely worded but urgent message to its many area customers: charge up your auto, now. John Vitale says he was happy to find out the cafe had opened after employees prepared the outage by baking bread and pastries.
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Those 29 counties are Alameda, Alpine, Amador, Butte, Calaveras, Colusa, Contra Costa, El Dorado, Glenn, Lake, Mariposa, Mendocino, Napa, Nevada, Placer, Plumas, San Joaquin, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, Shasta, Sierra, Solano, Sonoma, Stanislaus, Tehama, Tuolumne and Yuba. The city of San Francisco was outside of the shutoff zone as of Tuesday.
In California's wildfire season, the threat of fierce wind gusts and arid weather increase the chances of trees being toppled and falling into power lines - or those lines being blown into dry vegetation, sparking a fire. San Diego Gas & Electric has notified about 30,000 customers they could lose power in backcountry areas.
Almost 2 million people could be affected if there is a shutdown Wednesday, Liccardo said, as well as about 67 schools.
In addition to PG&E, utility company Southern California Edison is also turning off power to a small number of people in affected areas.
"We realize and understand the impact and the hardship", said Sumeet Singh, head of PG&E's Community Wildfire Safety Program.
Almost 500,000 Pacific Gas & Electric (PG&E) customers in Northern California were in the dark starting at midnight Wednesday as the company began shutting off power in an effort to help prevent starting a wildfire.
People preparing for the outages emptied shelves of bottled water and batteries, and there were lines at gas pumps. BART said its train operations have the "flexibility to pull power from other sections of our traction power supply system to replace power. and critical systems such as tunnel fans are also protected by a combination of installed and portable generators". Utility crews won't be able to inspect any power lines that might be damaged and restore electricity until after the severe weather has passed.