Chilly weather and damaging frost hovered over San Diego County valleys early Tuesday, and were expected again late Tuesday night into Wednesday morning.
A National Weather Service frost advisory affecting wind-sheltered valleys is scheduled to expire at 8 a.m. Wednesday.
Forecasters said a cold air mass would result in areas of frost as temperatures fall into the low to mid-30s in many locales -- except where northeast winds occur below passes and canyons. Temperatures early this morning dipped into the 40s along the coast and into the 30s in the valleys. Tuesday night will likely be just as cold in most areas, forecasters said.
"After a cold morning with frost in many valleys this morning, the clear skies and light winds will allow temperatures to fall efficiently again tonight,'' according to the weather service. "Take care to protect against frost.''
Below freezing temperatures are in the forecast for Wednesday morning. Temperatures are expected to drop to 22 degrees on Mount Laguna; 26 on Palomar Mountain; 28 in Julian; 29 in Ramona; 33 in Alpine; 35 in Oceanside; 37 in Escondido, Borrego Springs and Miramar; and 45 in San Diego, according to the NWS.
The frost could damage or kill sensitive, uncovered outdoor vegetation, according to the NWS. Pets should also be brought inside.
A warming trend is expected to begin Wednesday and continue through the weekend.
