Frost is seen on the ground in Ingersoll, Ont., in this photo from November 2012. (Betty Price / MyNews)

Environment Canada has issued a frost advisory for most of central and some of southern Ontario.

The temperatures are expected to drop to or near the freezing mark overnight tonight and could damage crops or gardens in areas, including Barrie - Orillia - Midland, Dufferin - Innisfil, Grey - Bruce, and York - Durham .

The City of Barrie is expected to drop to zero by 4 a.m. Saturday morning, and then slowly rise to a daytime high of 13 C by Saturday afternoon.

This is the first frost warning of the season for Simcoe County.