Hurricane Irma Facts, Damage, and Costs
Irma damage could have been $300 billion if it hit Miami
Hurricane Irma was one of the most powerful Atlantic hurricanes in recorded history. It was a Category 5 storm when it made landfall on Barbuda on September 6, 2017. Its winds were 185 miles per hour for 37 hours. An unofficial wind gust was clocked at 199 miles per hour. These winds extended 50 miles from the center.
Tropical-storm-force winds extended 185 miles from the center. Its coastal storm surges were 8 feet above normal tide levels. Above-average ocean temperatures of 86 degrees Fahrenheit sustained the storm. These temperatures are worsening due to global warming.
Irma held 7 trillion watts of energy. That's twice as much as all bombs used in World War II. Its force was so powerful that earthquake seismometers recorded it. It generated the most accumulated cyclone energy in a 24-hour period.
Irma's attack was the first time in 100 years that three storms Category 4 or larger hit the U.S. or its territories in the same year. Hurricane Harvey devastated Houston on August 25, 2017, and Hurricane Maria hit Puerto Rico on September 20.
President Trump declared emergencies in Florida, Puerto Rico, and the U.S. Virgin Islands. On September 6, Florida's governor ordered residents of the Keys to evacuate.
- September 6, 2017: Irma hit the Leeward Islands with winds over 180 miles per hour. The Prime Minister of Antigua and Barbuda described Barbuda as "barely habitable."
- September 7: Irma left hundreds in Puerto Rico without power. It hit the northern part of Haiti and the Dominican Republic with 15 inches of rain.
- September 8: Irma remained a Category 5 hurricane with a wind of 175 miles per hour. It affected the Turks and Caicos Islands and the eastern Bahamas. The storm passed over waters warmer than 86 degrees Fahrenheit. Barbuda's government issued a watch for Hurricane Jose.
- September 9: Irma affected the north coast of Cuba, flooding Havana. Winds hit approximately 150 miles per hour and waves reached up to 36 feet. Wind gusts of 55 miles per hour hit southeast Florida. The storm was downgraded to a Category 3 but was projected to regain strength before hitting Florida.
- September 10: Irma was upgraded to a Category 4. It hit Cudjoe Key, 20 miles north of Key West, and then Naples. Miami didn't get the core of Irma but still received life-threatening conditions. The Florida Keys received approximately 12 inches of rain and a 10-foot storm surge. Rainfall averaged 10 to 15 inches.
- September 11: Irma was downgraded to a Category 1 hurricane as it headed to Tampa, where it left 12 million people without power. Irma was then downgraded to a tropical storm as it hit Georgia, where 1.5 million lost power. The state had ordered people to begin evacuating on September 9.
The Facts on Hurricane Irma's Damage
Irma's death toll included 129 people in Florida, Georgia, and North Carolina. Florida officials ordered over 6.5 million people to evacuate. The Red Cross reported more than 550,000 overnight shelter stays related to the hurricane.
Irma damaged 95% of the buildings on Barbuda. It destroyed almost all communication and left much of the island uninhabitable. Many of its residents fled to Antigua.
Irma's total cost to the U.S. alone was $50 billion when adjusted for inflation. If such a storm were to hit Miami, the damage could reach $300 billion, according to insurance firm Swiss Re in a report examining the damage caused by 1992's Hurricane Andrew.
Irma threatened losses of up to $2.5 billion for Florida's agricultural produce. The state is America's second-largest grower of vegetables like tomatoes, green beans, and cucumbers. The potential shortage pushed orange juice futures and sugar prices higher in the days leading up to the storm. If Irma had hit Georgia and the Carolinas hard enough, it would have affected corn, soybeans, cotton, and peanut prices.
Fort Pierce, Florida, received 21.66 inches of rain, the most in the state. The strongest winds at 142 miles per hour hit Naples. Winds were 73 miles per hour in Miami. Three cranes collapsed and streets flooded.
Miami-Dade, Monroe, and Broward counties' building codes have the nation's highest wind standards. They improved their preparation after Hurricane Andrew hit in 1992. But that might not offer enough protection as hurricanes grow more powerful. “There’s no structure in Miami that’s built to withstand 185 mph winds,” Keith Wolfe, president of U.S. property and casualty for Swiss Re, told the Miami Herald.
As The New York Times reported, roughly 70% of the region’s buildings were built before 1994. Many of them have not been retrofitted. Even high-rises built to higher wind codes will suffer from heavy rains that seep in through roofs.
Irma could have done more damage, but Florida learned from Hurricane Charley in 2004 and Hurricane Andrew in 1992. The state revamped building codes to make houses more resilient to hurricanes. As a result, 80% of the homes in Irma's path were built to better withstand the storms.
Despite the new codes, Florida is the second-highest-cost state for homeowners insurance. The state trails only Louisiana.
3 Ways Climate Change Made Irma Worse
Climate change contributed to Irma's impact in three critical ways. First, rising sea levels worsened storm surges and flooding. Between 1880 and 2015, the average global sea level rose 8.9 inches. For perspective, Swiss Re estimates that a 3.34-inch rise in sea level could nearly double the costs of damages from hurricane-related storm surges.
Second, South Florida’s average August 2017 temperature was four-tenths of a degree above normal. Miami's average temperature for August was the warmest during that period on record, and temperature records were broken across the state. Seven of the past 10 summers have been above normal.
Warmer air holds more moisture, leading to greater build-up leading up to a storm. When this warm air releases the moisture, the water falls in torrents. This creates greater rainfall during a hurricane.
Third, global warming slows weather patterns. It allows hurricanes to hover over an area longer. In fact, storms have slowed down by 10% since 1949. This is caused by a weakened jet stream—a river of wind high in the atmosphere that races from west to east at speeds up to 275 miles an hour. It undulates north and south as it goes, driven by temperature contrasts between the Arctic and temperate zones. Since the Arctic is warming faster than the rest of the globe, it slows down the jet stream, allowing storms like Irma to move much slower than normal and wreak more havoc as they linger.
MIT models foresee more hurricanes developing from climate change in the decades ahead. Extreme storms with winds above 190 miles per hour are likely to form. That's more powerful than a Category 5, leading many meteorologists to call for a Category 6 designation.
How Irma's Damage Compares to Other Hurricanes
Irma was one of the most powerful Atlantic hurricanes, but it wasn't the most destructive because it skipped the most developed cities in Florida.
Here are the five most economically devastating hurricanes in U.S. history.
- The most destructive hurricane was Hurricane Katrina. It cost $160 billion when adjusted for inflation. It was a Category 5 hurricane that flooded New Orleans in 2005. Most of the damage was caused by storm surges that overwhelmed the levee system.
- Hurricane Harvey cost $125 billion. It was a Category 4 hurricane that dropped more than 50 inches of rain. The resultant flooding covered two-thirds of Houston, Texas, in August 2017.
- Hurricane Maria is the third-worst, creating $90 billion in damage. It devastated Puerto Rico a few weeks after Irma hit.
- Hurricane Sandy hit New York and New Jersey in 2012. It left $70.2 billion in damage. Although it was a tropical storm, not quite a hurricane, it hit highly developed areas.
- Hurricane Irma is the fifth-costliest storm, at $50 billion.