A stretch of potentially hazardous weather is spanning much of California through the weekend, with gusty winds, red flag conditions and the risk of additional power shutoffs — already in place for thousands — to avoid sparking any deadly wildfires.

From Redding to Riverside, forecasters are warning of a strong offshore flow through at least Saturday, with gusts as high as 40 and 50 mph drying out huge swaths of California and triggering utility shutoffs in the most vulnerable areas. In Southern California, the conditions are creating the infamous Santa Ana winds, often the culprit for some of the region’s most dangerous late-season fires.

According to a red flag warning issued for Southern California, “if fire ignition occurs, conditions are favorable for rapid fire spread and extreme fire behavior which would threaten life and property.”

Across Northern California, Pacific Gas and Electric initiated a public safety power shutoff Thursday afternoon, with about 13,000 customers cut off and 7,000 still under consideration for additional shutoffs Friday, according to PG&E’s latest update. The shutoffs were initiated across the northern Sacramento Valley, along the inland Bay Area and even down into Santa Barbara County, the utility’s outage map showed.

Southern California Edison, which provides power to about 15 million people in the Southland, said it was considering similar power shutoffs for more than 120,000 customers across seven counties, including Los Angeles, Orange and San Bernardino. About 400 customers in Inyo and Mono counties were already shut off, “due to heightened wildfire risk,” the company reported.

The state’s big three investor-owned utilities, PG&E, SCE and San Diego Gas & Electric, have adopted a strategy in the last decade of de-energizing their lines where their equipment is at risk of malfunctioning during powerful winds and sparking a fire. Many of California’s deadliest and most destructive fires were started by utility equipment.

Diane Castro, a spokesperson with Southern California Edison, said shutoffs are possible through Saturday afternoon. PG&E said its shutoffs would likely be required through Saturday.

Winds across the state began to pick up late Thursday as a low pressure system moved down the state from the Pacific Northwest, particularly so in Northern California where the weather service recorded gusts hitting 63 mph at Mt. St. Helena, 45 mph at Los Vaqueros Reservoir and 48 mph at Mt. Diablo.

Much of the Bay Area and Sacramento Valley remain under a red flag warning through Saturday evening, with wind gusts up to 55 and 65 mph expected along some of the highest peaks and sustained winds up to 25 to 35 mph, according to the weather service.

“Despite recent cool weather and high humidity, we are expecting a widespread and prolonged offshore wind event which will likely dry fuels out very quickly,” the region’s red flag warning said.

While the offshore flow will slightly raise overnight temperatures, pushing out any marine layer influence, overall temperatures in the area won’t increase, said Joe Merchant, a National Weather Service meteorologist in Monterey.

“Usually people do associate fire weather concerns with hot temperatures… [but] temperatures are going to feel relatively normal for this time of year,” Merchant said. “That doesn’t mean we can’t have critical fire weather concerns.”

He said area plants and brush are at record-low moisture levels, which means any fire could rapidly spread.

On Thursday in northern Los Angeles County, wind gusts peaked at 56 mph at Lake Palmdale, with blustering winds recorded along the Central Coast and into the Antelope Valley, the weather service said. Conditions were expected to intensify Friday.

The Santa Ana pattern of winds is creating red flag conditions across the mountains and valleys in Los Angeles and Ventura counties Friday and Saturday, the weather service warned.

“Gusts between 30 and 45 mph will be common over much of Los Angeles and Ventura counties, with isolated gusts to around 50 mph,” the red flag warning said. “Winds will be strongest in the valleys and mountains.”

Those high winds coupled with low relative humidity, “will support rapid fire growth and erratic fire behavior,” the warning said.

The San Bernardino and Riverside county valleys and mountains are also under a red flag warning through Saturday.

In Orange County, the Santa Ana mountains are facing similar windy conditions, but forecasters said the recent Airport fire eliminated much of the available brush, making the area less ripe for fire spread.

Farther east, parts of southwest California aren’t necessarily facing those critical fire conditions, but gusty winds — similarly up to 50- and 60-mph gusts — are still expected through Saturday. A wind advisory for the Mojave Desert, Coachella Valley and inland areas is warning that tree limbs could fall, unplanned power outages were possible and driving could be difficult, especially for high-profile vehicles.