Frequency and Intensity of Hurricanes Within Florida’s Threat Zone

Abstract

This chapter examines historical hurricanes within Florida’s threat zone; a 1,000 km radius around 26∘N latitude and 82∘W longitude. The area is visited by hurricanes from May through December with a peak in September. Threats come from hurricanes originating or passing over the Gulf of Mexico, Caribbean Sea, and the Bahamas. On average, three hurricanes every 2 years and one major hurricane every other year occur in the threat zone. Hurricane Wilma in 2005 is the strongest hurricane in the record with a peak intensity of 78.4 m s− 1. This is approximately a one-in-20 year event for the threat zone as a whole. The region can expect hurricane wind intensities of 60.8 m s− 1 (58.3–63.3) (90% CI), on average, once every 2 years. There appears to be no upward or downward trend in the frequency of hurricanes within the region, but the intensity of hurricanes is on the rise. The rise could be related to recent (since 1980) warming ocean temperatures in the Caribbean, but a simple linear regression model finds no statistically significant signal. Hurricanes over and around Florida are intensifying and decaying more rapidly than in the past. Explanations for these changes are lacking but they suggest a bias in risk models that assume a stationary hurricane climate over and around Florida.