LOS ANGELES (AP) — More rain fell Monday on parts of Southern California after causing mudflows over the weekend, helping firefighters but boosting the risk of toxic ash runoff in areas scorched by Los Angeles-area wildfires.

Less than an inch of rain fell in most areas, but it was enough to loosen Los Angeles hillsides burned bare by the recent blaze near the Pacific Palisades.

Apparently "authorities never find the source of ignition for more than half of all wildfires in the Western U.S.," a "knowledge gap that can hamper prevention efforts." "Fires break out in the wooded areas on the edges of Los Angeles all the time,

Cool, wet weather has spread through Los Angeles County, bringing intermittent rain showers and a chance of isolated thunderstorms through Monday, with gusty winds and perhaps even some small hail. Areas affected by the Palisades and Eaton fires are under a flood watch through Monday afternoon.