LOS ANGELES — 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.

The rain that is expected to hit the scorched Los Angeles landscape this weekend may bring relief to the fire fights, but it could also bring flash floods and mudslides. Although forecasts show that the risk is relatively low, local officials are taking the warnings seriously.

Southern California is about to get its first significant rainfall in months, bringing desperately needed relief after dry conditions and hazardous winds fueled a series of wildfires in January. The rain could start as early as Saturday afternoon and last through Monday night with the heaviest rain coming on Sunday,