Use this map to help you estimate the average date on which you can expect the last frost to occur in spring.  A frost is defined as a light freeze of temperatures ranging from 29 to 32 degrees F. (-2 to 0 degrees C)

Based on statistics, there is a chance that a frost will occur outside of the dates listed.  Whether or not a specific plant will be damaged depends on the type of plant, the maturity of the plant, the temperature, the duration, as well as many other variables. Remember that nature and the weather are unpredictable.