On the basis of 40 years of tornado history and more than 100 years of weather history, the United States has been divided into four zones that geographically reflect the number and strength of extreme windstorms. This map shows the four zones. Zone IV has experienced the most and the strongest tornado activity. Zone III has experienced significant tornado activity and also includes coastal areas that are susceptible to hurricanes.
The National Weather Service Storm Prediction Center has also produced a map that shows tornado activity in the United States.
Taking Shelter from the Storm: Building a Safe Room Inside Your House uses this data and shows you how to assess your risk of being hit by a tornado or hurricane. You can download the publication or order a copy by calling 1-888-565-3896.
To learn more about the wind history for the area where you live, check with local building officials, meteorologists, emergency management officials, or the local television weather reporter.