Hurricane Rosa weakened slightly but was still a major hurricane Friday as as it churned toward the Mexican coast, the National Hurricane Center said.
In Los Angeles and Orange counties, surf could build up to eight feet high by late Saturday, and up to 10 feet Sunday and Monday on south-facing beaches.
Rosa, with maximum sustained winds decreasing to nearly 120 miles per hour (195 kph), was now a Category 3 storm, coming down a notch on the five-step Saffir-Simpson Hurricane Wind Scale. The storm was moving west at 13 miles per hour.
The center of Rosa was expected to approach Baja California Monday, but is forecast to weaken to a tropical storm by that point.
"Heavy rainfall associated with Rosa or its remnants is expected to affect parts of the southwest United States by early next week, which could cause flooding in this region", the National Hurricane Center said.
Up to 4 inches could fall in Flagstaff, Payson and Prescott through Wednesday.
Previously a powerful Category 4 hurricane with sustained winds of 140 miles per hour, Rosa weakened over the weekend and is expected to bring potentially heavy rain, blustery winds and thunderstorms to the Valley from Sunday through Tuesday, forecasters said. Harvey, which made landfall north of Corpus Christi late Friday evening, is expected to dump upwards to 40 inches of rain in Texas over the next couple of days.