The NY Times discusses this issue. Some excerpts below
Why did so many wildfires break out at about the same time?
Forecasters warned for days before the first fires erupted last week that fire danger would be very high. They cautioned that wind gusts could reach 50 to 80 miles an hour, and even 100 m.p.h. or more in some places in the mountains. And vegetation built up over two consecutive wet winters had turned to tinder after months of drought this year. The combination of high winds, dry air and ample fuel combined to make a critical fire-weather event likely in Southern California.
Late fall and early winter tend to be when catastrophic fires are most likely to break out in California. Cooler weather coincides with the arrival of Santa Ana winds, the strong, dry gusts that blow southwest from Nevada and Utah into Southern California and are linked to the region’s most devastating fires.
The deadliest and most destructive fire in California’s recent history, which destroyed the town of Paradise in the foothills of the Sierras, broke out in mid-November 2018.
Excerpt about the Palisades fire:
Investigators have made it clear that it could take time to reach firm conclusions about the cause of the fire.
The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives, which is taking the lead, took more than a year to report conclusions about the Maui fire.
“We are looking at every angle,” Dominic Choi, the assistant Los Angeles police chief, said on Monday about the fires burning across the region. He said that arson had not been ruled out for any of them. In the case of the Palisades fire, he added, “there has been no definitive determination that it is arson.”
For now, the entire area around the investigation site is eerily empty. The neighborhoods near the trail are evacuated and dozens of houses were leveled; — the only signs of life there are a few fire trucks and an occasional police patrol.
Further down the hillsides, toward the ocean, there is utter devastation. Entire neighborhoods have been flattened, their subdivisions now just a grid of ash.