Valleys and deserts in San Diego County can expect an even deeper chill through Friday, according to the National Weather Service.
After storms late Wednesday and early Thursday, winds will continue to decrease and become light in most areas, but temperatures will fall to as low as 32 degrees in wind-sheltered valleys. The cold will result in frost formation, especially in grassy and mulch areas.
The frost advisory will be in effect from 10 p.m. Thursday to 8 a.m. Friday. Impacted cities and communities include Escondido, El Cajon, San Marcos, La Mesa, Santee, Poway and Borrego Springs.
Forecasters warn that frost could kill sensitive outdoor plants and vegetation if left uncovered. Pets should be brought indoors.
For the weekend, patchy frost is predicted for late Friday and Saturday morning.