Wind Speeds

Ultimate Design Wind Speed Map Notes: (All Categories)

  1. Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 feet (10 miles) above ground for Exposure C category. (Exposure categories to be utilized for design shall be in accordance with Section 1609.4 of the Florida Building Code, 6th Edition 2017, Building).
  2. Linear interpolation between contours is permitted.
  3. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
  4. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.

Risk Categories

RiskDescription

Risk Category I 

5 Wind speeds correspond to approximately a 15% probability of exceedance in 50 years. (Annual Exceedance Probability equals 0.00333, MRI equals 300 years).
Risk Category II 5 Wind speeds correspond to approximately a 7% probability of exceedance in 50 years. (Annual Exceedance Probability equals 0.00143, MRI equals 700 years).
Risk Category III and IV 5 Wind speeds correspond to approximately a 3% probability of exceedance in 50 years. (Annual Exceedance Probability equals 0.000588, MRI equals 1700 years).


Basic Wind Speed

The basic wind speed in miles per hour, for the development of wind loads, shall be determined from Figure 1609.3 (1)(2)(3). The exact location of wind speed lines shall be established by local ordinance using recognized physical landmarks such as roads, canals, rivers and lake shores whenever possible. Because of the many wind speed lines of the multiple Risk Categories, there are not appropriate physical landmarks to provide an accurate and orderly reflection of these boundaries. To determine the applicable wind speed of a particular parcel, Palm Beach County has developed separate Geographic Information Systems (GIS) tools for each of the Risk Categories.

Wind-Borne Debris Region

Areas within hurricane-prone regions located:

  • Within 1 mile (1.61 kilometers) of the coastal mean high water line where the ultimate design wind speed Vult is 130 mph (48 m/s) or greater or
  • In areas where the ultimate design wind speed Vult is 140 mph (53 m/s) or greater. Linear interpolation between contours may not be utilized in the determination of the Wind Borne Debris Region. All of Unincorporated Palm Beach County is within the Wind Borne Debris Region.