There’s a frost advisory in effect for the Southeastern interior of Mendocino County and Southern Lake County, including Middletown, Calpella, Hidden Valley Lake, Knobcone Camp, Finley, Lakeport, Hopland, Clearlake, Clearlake Park, Redwood Valley, Talmage, and Ukiah, from 2 am Thursday morning until around 9 am. Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered.