**This is not a guaranteed date** Each winter, on average, your risk of frost is from October 25 through April 17. Almost certainly, however, you will receive frost from November 12 through April 7. You are almost guaranteed that you will not get frost from April 26 through October 6. Your frost-free growing season is around 191 days.
Frost occurs when temperatures dip below freezing. Frost kills tender annual plants, such as tomatoes, peppers, impatiens, marigolds, and more. (Perennials have tougher roots and tops, and survive the winter.)
When a light frost threatens—one in which the temperatures dip just below 32 degrees for a short period of time—be sure to cover tender plants with plastic or bring indoors if possible.
A hard frost, also called a killing frost, is when temperatures get below 28 degrees for several hours. This type of frost kills all annuals, even those that will tolerate a light frost. Also, there’s little you can do to protect annuals from a hard frost.