Why Category 1 Hurricanes Can Cause As Much Damage As the Strongest Hurricanes

While Hurricane Ernesto was a Category 1 storm, knocking out power to 40% of Puerto Rico and causing flash flooding, scientists stressed that lower-level storms can cause damage comparable to a Category 5 hurricane. Hurricanes are rated from Category 1 to 5 on the Saffir-Simpson scale, with Category 5 being the most intense. The scale was developed in the 1970s by an engineer and meteorologist. Hurricanes are ranked based on sustained wind speeds, but the Saffir-Simpson scale does not take into account other impacts such as storm surge and rainfall. Hurricanes of any size can have both.

“Focusing too much on hurricane classification can be misleading,” said Craig Fugate, former director of the Federal Emergency Management Agency (FEMA) and now a crisis response consultant. “While Category 5 winds are undoubtedly devastating, the real danger lies in the storm’s other characteristics. There is a big risk of people underestimating the threat of a Category 1 hurricane because of its low classification. Focusing on wind speeds can lead to a false sense of security.”

Category 1 hurricanes like Ernesto can cause dangerous storm surges, catastrophic flooding, and tornadoes, leading to infrastructure damage like power outages, road closures, and water pollution, among other serious, long-term impacts. In fact, the greatest threat to life comes from storm surge, caused by ocean water being pushed ashore by the storm’s winds. Water levels can rise at least 30 feet. One study found that 49 percent of hurricane-related deaths in the United States were caused by storm surge, 27 percent by flooding from heavy rains, and only 8 percent by wind.

“Most of the damage comes from water, not wind,” said Michael Wehner, a scientist at Lawrence Berkeley National Laboratory who studies how extreme weather events change. “The problem is that the Saffir-Simpson scale simply measures the highest wind speed at any given moment in a storm.”

Additionally, experts are concerned about public safety when classifying storms based on wind speed. Category 3 and above hurricanes are considered major hurricanes by the National Weather Service, meaning the public may consider lower levels to be unimportant. What is more important is the size of the storm rather than the wind speed. Category 1 hurricanes can cause major damage even at wind speeds below 95 mph. Hurricane Debby, a Category 1 storm, killed five people with initial damage estimates ranging from $12.3 billion to $28 billion. Hurricane Sandy, also classified as a Category 1, was the fifth costliest storm to ever hit the United States, with total damage of $88.5 billion.

Katrina, which killed more than 1,800 people, made landfall in Louisiana as a Category 3 storm after weakening from a Category 5 at sea. The storm brought flooding 25 to 28 feet above normal tide levels in Mississippi, and 10 to 20 feet in southeast Louisiana. Katrina’s ominous name suggests that storm surge can be the single largest cause of loss of life in a hurricane, according to the National Hurricane Center (NHC). “A Category 1 hurricane can still cause significant damage to local communities, especially those living in floodplains and/or mobile homes,” said Xilei Zhao, a data analyst at the University of Florida who specializes in modeling evacuation behavior during hurricanes.

Improved storm surge forecasting could save lives, Jeane Camelo and Talea Mayo, authors of a study on the impact of the Saffir-Simpson scale, note. They also concluded that climate change could significantly increase the risk of storm surge in coastal areas. Because it has dominated hurricane classification for more than 50 years, the Saffir-Simpson scale has one major advantage: it is a measure that provides immediate visibility into the strength of a storm. But Wehner says the public needs to know that the Saffir-Simpson scale is not all-encompassing.