Gardeners are becoming more and more interested in keeping their gardens as productive as possible into the fall and winter months. Whether growing in the open garden or using season extenders like traditional cold frames or the newer technology of row covers, low tunnels, and hoop houses, the first step in late season gardening success is knowing when the first fall frost is likely to strike.
This information is easily available in graphic or tabular form from the National Climatic Data Center. Check out a nation-wide map of showing when you can expect temperatures of either 28 degrees F or 32 degrees F to help you figure out when plants need to be started in order to harvest a fall or winter crop. Also included are maps of the spring frost dates and frost-free season length. The tabular data lists three probabilities for the fall dates of 36, 32, and 28 degree temperatures for many locations within each state.