National Weather Service United States Department of Commerce
Frost/Freeze Program
The frost/freeze headline season has started across Downeast Maine.  The program will expand to central and parts of northern Maine on  Thursday, May 21st.  The program will begin across far northwest Maine on June 1st this year.  The earlier than usual start dates are due to an earlier than usual green-up. The dates that appear on the map below are therefore the latest dates that the frost/freeze program will commence for a zone.
Below are the thresholds that the National Weather Service Forecast office in Caribou uses when issuing frost advisories and freeze
warnings. Also included is a map of the dates the program usually begins each spring, and is based on the latest 1981-2010 climate normals.