The National Weather Service has issued a fire weather watch for most of extreme southwestern California starting late Wednesday evening and lasting through 8 p.m. Friday evening.

This prompted Southern California Edison to expand the area that could have power cut as a fire-safety measure — affecting as many as 106,000 customers.

Low humidity of 5% to 10% and strong, gusty Santa Ana winds are to blame for the elevated fire risk along coastal mountain slopes and inland valleys. East to northeast winds will reach speeds of 20 to 30 mph, with gusts of 35 to 50 mph, and isolated gusts of up to 60 mph.