While the first frost and last frost in any given area is a moving target, there are guides that will tell you the approximate dates. The last frost date is important in the spring for knowing when to start seeds, and when it is safe (or theoretically safe)to put out tender annuals and vegetables.
It is also important to know your last approximate frost date for the fall. There are a lot of fruits, vegetables and herbs that need to be harvested before the first frost. There are also lots of ways to protect your plants from frost, but you need to be ready by knowing what your probable last frost date will be.Fortunately, there are several great resources to find out this information. Local nurseries and cooperative extension services can give you very accurate local frost dates. There are also some interactive websites where you can plug in your zip code and get your areas frost dates. Farmers' Almanac Frost Dates Victory Seed Frost Date Chart