SAN DIEGO — It may have been sunny and clear Thursday afternoon, but cooler temperatures, gusty winds and rain is on the way.

A fast-moving low-pressure system will swoop over Southern California this evening, bringing scattered showers and a chance of thunderstorms into early Friday.

Ahead of the storm will be strong west to northwest winds, especially for the county’s mountains and deserts, where a wind advisory is in place until 6 p.m. Friday. Gusts could reach 40 to 60 mph in those isolated areas, and gusts up to 30 mph along the beaches and inland valleys.

For those in the mountain communities, light rain could develop as early as 9 p.m. this evening, but the bulk of the rain will move across San Diego County while most are sleeping (between midnight through sunrise Friday).

There may be a few stray showers in East County early Friday afternoon as the system moves southeast.

Rain totals will be light with this late-season system: 0.10-0.2″ at the coast, 0.2-0.3″ for inland valleys, 0.3-0.4″ in our mountains and less than a 0.1″ for deserts. A few inches of snow could fall above 7,000 feet, but a light dusting is possible around 5,500 feet Friday morning.

Temperatures will be the coolest on Friday, but then high pressure builds into the weekend and will bring warmer temperatures and dry conditions through the middle of next week.