Many counties in northern and central California will face power outages from midnight Wednesday in an effort to reduce wildfires that are caused by dry winds that down power lines.

In the largest preventive outage in state history, two California power utilities will cut power to more than 900,000 customers from Wednesday midnight to curb new wildfires. Pacific Gas & Electric utility (PG&E) will turn off power to about 34 northern and central counties in California affecting close to 800,000 people while the Southern California Edison said it will cut power to more than 100,000 customers in 8 counties. 

Dry and windy weather forecasts coupled with a high risk of fire had led to the preventive outage which will last for several days. 

"Given the prolonged period during which the wind event will unfold, and the large number of power line miles that will need to be inspected before restoration, customers are being asked to prepare for an extended outage," PG&E said in a release.

The National Weather Service has warned extreme fire weather conditions in California for Wednesday and Thursday. The residents in these areas were asked to be vigilant by the California Department of Forestry & Fire Protection as the period between October to December witness the most destructive and deadliest fires. The Department has also increased staffing to deal with the wildfire issue.

San Jose Mayor Sam Liccardo urged residents as well as businesses to prepare for life without electricity for a prolonged period.

"Some of what we need to do to get ready will in fact take years," Liccardo said. "That is ensuring we have sufficient backup power generation, establishing microgrids where we can do so, things of that nature."

Residents have been urged by authorities to keep emergency kits with flashlights and batteries ready, along with first aid supplies and cash. Residents are also being pushed to create an emergency plan which includes food and water for all members of the family and even pets.

San Francisco is the only county in the bay area, which will not be affected by the power cut. 

Last month almost 48,000 people faced power cuts in California due to dry and windy conditions, the second consecutive power cut that took place in a week.

Power Lines in South Africa Electricity pylons carry power from Cape Town's Koeberg nuclear power plant. Photo: Reuters/Mike Hutchings