Strong winds, with gusts as high as 84 mph in the San Gabriel Mountains, began blowing their way through Southern California on Tuesday, apparently tipping over a big rig and its trailer on the 60 Freeway in Jurupa Valley and threatening thousands of customers to possibly face power shutdowns as a precaution to wildfires.

Los Angeles city firefighters battled a wind-driven blaze in Pacific Palisades that within hours had charred 1,200 acres, damaged homes on a hillside and prompted 30,000 people to evacuate.

President Joe Biden was set to speak in eastern Riverside County early Tuesday afternoon, but the event was canceled because of the weather, White House spokesperson Nicolette Jaworski said. That desert region was seeing heavy winds, causing concerns about fire danger.

Southern California Edison was considering power shutoffs throughout Southern California. Such intentional outages are meant to keep electrical equipment from malfunctioning in high winds and causing wildfires.

At 4 p.m., the so-called public-safety power shutoffs were affecting 6,801 customers in Los Angeles County, 64 in Orange County and 731 in Riverside County. More than 411,000 customers were being considered for shutoffs: 122,070 in Riverside County, 111,188 in Los Angeles County, 67,233 in San Bernardino County, and 12,805 in Orange County.

For the latest from that utility, see sce.com.

Meteorologist Sebastian Westerink with the National Weather Service said that the strongest winds had yet to swirl in the Inland Empire.

“We are expecting the worst of the winds for the Inland Empire, the San Bernardino County foothills tomorrow (Wednesday) morning through early in the afternoon,” Westerink said. “We specifically issued a particularly dangerous situation, that we really rarely issue. And it’s kind of to emphasize a level of heightened risk above that of a red flag warning.”

The winds will continue to be widespread on Thursday, but not to the extent experienced on Wednesday.

“We’re warning of a particularly dangerous situation where we will have severe, widespread strong winds, accompanied with very dry air,” the meteorologist said. “We’ll have some pretty dangerous fire conditions, especially in that time frame tomorrow (Wednesday), 7 a.m. to 1 p.m.,” he said.

The offshore winds were anticipated to be dry and strong, the National Weather Service said, while labeling the event a “life-threatening and destructive windstorm.”

A red-flag warning, trumpeting extreme fire danger, was in effect as were high-wind and fire watches.

By 1 p.m. Tuesday, some areas in L.A. County had seen wind gusts above 50 mph, including in the San Gabriel Mountains, where Mount Lukens Truck Trail and Henniger Flats above Sierra Madre each experienced 79-mph winds.

In the western San Gabriel Mountains, Magic Mountain Truck Trail (84 mph), Dexter Park Road above San Fernando (63 mph) and Eaton Canyon near Pasadena (62 mph) had also seen some of the highest early wind gusts, according to NWS data.

The National Weather Service bureau covering L.A. and Ventura counties warned of the potential for downed trees, dangerous sea conditions along the coast, knocked over big rigs and some airport delays and turbulence at Los Angeles International, Burbank and Long Beach airports.

Forecasters advised residents to secure loose objects, to park cars away from trees and to charge necessary electronic and light devices.

Both Gov. Gavin Newsom and the Department of Forestry and Fire Protection, or Cal Fire, have moved firefighting resources from Northern California to Southern California in preparation for the critical fire weather. Teams in San Bernardino, San Diego and Riverside counties planned to increase their staffing, officials said.

In Pasadena, officials canceled all events and activities scheduled for Tuesday at city-owned community and recreation centers and were considering potential closures for today as well.

The Los Angeles Unified School District moved Topanga Elementary School students to Woodland Hills Academy in the San Fernando Valley out of an abundance of caution, an LAUSD spokesperson said. Also, Caltrans was closing Topanga Canyon Boulevard between Mulholland Drive and Pacific Coast Highway until 6 p.m. Friday.