Drenching rains fell over parts of Southern California’s mountains and deserts Saturday. Photo via @NWSSanDiego Twitter

Monsoon moisture remains firmly in place Monday across San Diego County, and may fuel showers and thunderstorms with flash flooding possible, the National Weather Service said.

“Scattered thunderstorms will continue for the mountains and deserts today from late morning into the evening with coverage more isolated for Tuesday as drying occurs,” the weather service said early Monday.

The chance of rain ranges from 20% in the western valleys to 40% in the mountains and 30% in the deserts.

High temperatures on Monday were predicted to be 75 to 80 near the coast, 80 to 85 inland, 82 to 87 in the western valleys, 87 to 92 near the foothills, 83 to 90 in the mountains and 100 to 105, according to the weather agency.

The atmosphere may dry out a bit and become more stable through midweek as high pressure builds, the weather service said. This could result in some warming, but monsoon flow was likely to return late in the week as high pressure drifts east, and opens the door for more clouds, showers and thunderstorms.

Hurricane Frank could generate hazardous surf conditions, including strong rip currents, Sunday night through Wednesday.

A 4-5 foot south swell from 180-200 degrees at a period of 12-14  seconds will generate surf of 4-7 feet, mainly along south- facing beaches, and strong rip and longshore currents at all beaches, through Wednesday.

Updated at 7:10 a.m., Monday, Aug. 1, 2022

City News Service contributed to this article.