By Staff Report POSTED: July 13, 2010 12:55 p.m. / The Saffir-Simpson scale has five categories of strength. View Larger A hurricane’s strength is ranked on a scale of 1 to 5, a system known as the Saffir-Simpson Scale. Categories are determined by barometric pressure (in inches) in the center of the hurricane, wind speed, storm surge, and extent of damage.