San Luis Obispo, CA -- The National Weather Service has issued a frost advisory covering San Luis Obispo County effective through 9 a.m. this morning. Temps are expected to be between 29 and 32 degrees tomorrow as well. The coldest temperatures are expected in San Luis Obispo, Pismo Beach, Morro Bay, Cambria, San Simeon, Santa Maria, Lompoc and the Vandenberg Air Force Base area.