Hurricane Irma Facts, Damage, and Costs
Irma Damage Could Have Been $300 Billion If it Hit Miami
Hurricane Irma was the most powerful Atlantic hurricane 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 20 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.
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 mph. 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 mph. 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 at approximately 150 mph and waves of up to 36 feet. Wind gusts of 55 mph 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 downgraded to a Category 1 hurricane as it headed to Tampa. Twelve million people were without power. Irma was downgraded to a tropical storm as it hit Georgia. There were 1.5 million people who lost power. The state had ordered people to begin evacuating on September 9.
The Facts on Hurricane Irma's Damage
Irma damaged 90% of the buildings on Barbuda. It destroyed almost all communication and left 60% of the population homeless. The government evacuated 1,800 citizens to Antigua.
Irma's total cost was $50 billion when adjusted for inflation. If Irma had hit Miami, the damage could have reached $300 billion, according to insurance firm, Swiss Re.
Irma threatened $1.2 billion in Florida's produce crops. 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.
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,” stated Keith Wolfe, president U.S. property and casualty for Swiss Re.
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 would 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 highest-cost state for homeowners insurance. Floridians paid an average $3,575 on a $200,000 policy with a $1,000 deductible. That's double the national average.
Three Ways Climate Change Made Irma Worse
Climate change contributed to Irma's impact in three ways. First, rising sea levels worsened storm surges and flooding. Between 1880 and 2015, the average global sea level has risen 8.9 inches. That increase doubles the cost of damage from hurricane-related storm surges, according to Swiss Re estimates. Around Florida, the sea level is rising six times faster than average. Although most of that is due to El Nino and other regional variations, climate change aggravates these natural cycles. As a result, Miami Beach now floods during "king" tides.
Second, South Florida’s average August 2017 temperature was four-tenths of a degree above normal. Florida’s average temperature from January through April 2017 was the warmest during that period on record. The 2016 season was the warmest since 2010 in South Florida. Seven of the past 10 summers have been above normal.
Warmer air holds more moisture, so it's less likely to rain. But 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. That’s 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. It's driven by temperature contrasts between the Arctic and temperate zones. But the Arctic is warming faster than the rest of the globe. That slows down the jet stream. That allowed Irma to move much slower than normal. They had more time to wreak damage.
M.I.T. models foresee more hurricanes developing from climate change by 2035. Of those, 11% will be Category 3, 4, or 5. By that time, 32 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 the most powerful Atlantic hurricane, but it wasn't the most destructive. It skipped the most developed cities in Florida. If it had squarely hit Miami when it was still Category 5, the damage would have been $300 billion. That estimate includes damage to buildings and their contents. It also included the economic cost of interruptions to business and additional living expenses.
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 most costly storm at $50 billion.
Swiss Re. "Hurricane Andrew: The 20 Miles That Saved Miami." Accessed July 29, 2020.