Hurricane categories are based on wind speed, but the worst damage usually comes from water. Photos show the real damage storms can do at different strengths.

satellite image shows hurricane forming a cyclone of clouds above the gulf of mexico in between the yucatan peninsula and florida
Hurricane Idalia is seen barreling toward Florida as a Category 1 storm on Tuesday, August 29, 2023.NASA/GOES-East
  • Wind speed determines hurricane categories — not the rain, storm surge, or flooding they can cause.

  • Category 1 storms can still kill people, destroy homes, and leave lasting damage in their wake.

  • These photos show the differences between hurricane categories, using memorable storms as examples.

Hurricanes Irma and Harvey were two very different storms.

animated satellite images show a caribbean beach before and after hurricane irma hit
Anse Marcel Beach in Saint Martin before Hurricane Irma on August 25, 2016, and the storm on September 11, 2017.Satellite image ©2019 Maxar Technologies

While Harvey's record rainfall drenched southeastern Texas and western Louisiana in 2017, flooding Houston in over 4 feet of water, Irma's winds flattened buildings, trees, and power lines on the Caribbean islands it devoured.

At its peak, Harvey was a Category 4 hurricane on the Saffir-Simpson scale, but its weakened winds downgraded it to a tropical storm the day after it made landfall.

Irma was a Category 5 monster that was one of the strongest Atlantic hurricanes ever recorded. Both had widespread devastation even though they were on the opposite ends of the category scale.

Hal Needham, a hurricane scientist at Louisiana State University, explained on the weather site WXshift in 2017 that a storm's category doesn't fully convey how much damage it could cause.

"Hurricanes and tropical storms throw three hazards at us: wind, rainfall, and storm surge," he wrote. "Think of the impacts separately. Storms with weaker winds are more likely to stall and dump heavier rainfall. This shocks people, as it would seem intuitive that a Category 5 hurricane would tend to dump more rain than a Category 1 hurricane. But the opposite is true."

Here's a closer look at the type of damage that storms at different categories can cause.

The Saffir-Simpson hurricane scale, which does not include lower-level tropical storms or tropical depressions, is based solely on maximum sustained wind.

hurricane categories on the Saffir-simpson scale go from 1 to 5, from 74 to 157 mph and can cause increasing damage as the category increases
Ana Pelisson/Business Insider

Source: NHC

Once a tropical storm's winds exceed 39 mph, the storm gets a name.

hurricanes us map 1950-2011 shows more lower category storms hitting the coast than higher ones
Hurricanes that have hit the continental US from 1950 to 2011, color-coded by category.NOAA

Most storms that make landfall in the US are tropical storms, not "major" hurricanes of Category 3 and above.

But "storms are too complex to define by one number," Needham wrote.

hurricane harvey floods houston and submerges a semi
Interstate 45 seen during widespread flooding in Houston on August 27, 2017.REUTERS/Richard Carson

While Harvey's strong winds on the Texas Gulf Coast caused widespread destruction, most of the devastation came after it was downgraded to a tropical storm, dumping feet of water on Texas and Louisiana.

While strong winds can rip shingles off roofs and tear down power lines, flooding often causes more widespread, costlier damage — and can be more dangerous for humans, no matter what the hurricane category is.

hurricane Harvey flooding in Houston covers homes up to the roofs
Homes surrounded by floodwater from Tropical Storm Harvey on August 29, 2017, in Houston.AP/David J. Phillip

Harvey, for example, was particularly devastating because it stalled over the Houston area, staying in roughly the same place for five days.

people use boats to navigate flooded streets during hurricane harvey
People float on floodwaters caused by Hurricane Harvey.David J. Phillip/AP

Category 1 hurricanes have wind speeds of 74 to 95 mph.

Water floods the roads in Rodanthe, North Carolina, after Hurricane Dorian hit the area on September 6, 2019.
Water floods the roads in Rodanthe, North Carolina, after Hurricane Dorian hit the area on September 6, 2019.Mark Wilson/Getty Images

They can damage a home's exterior, break large tree branches, and knock down power lines, causing multi-day power failures.

Hurricane Dorian was a Category 1 when it made landfall in North Carolina in 2019.

When Dorian hit the Bahamas days earlier, it was the second-strongest storm ever recorded in the Atlantic, with 185 mph winds.

The hurricane caused an estimated $3.4 billion in damage to the islands, a report from the Inter-American Development Bank found.

Category 2 hurricanes have wind speeds of 96 to 110 mph.

debris surrounds some homes still standing from hurricane ike damage in texas
Hurricane Ike's winds caused severe damage when the storm hit Texas in 2008.David J. Phillip/REUTERS

Storms of this intensity can cause major damage to homes and uproot large trees. They also generate power failures that last up to weeks.

Hurricane Ike was a Category 2 when it hit Texas in 2008.

While a hurricane's category classifies how strong it is, this definition can't fully predict how devastating it might be.

a home leans, destroyed in Hurricane Sandy in Connecticut
Hurricane Sandy caused the deaths of hundreds of people and cost $68 billion in damage.AP

Superstorm Sandy hit as a Category 3, but by the time it made landfall in New York and New Jersey in 2012 it had weakened to a post-tropical cyclone.

Category 3 storms have wind speeds of 111 to 129 mph.

Burned houses are seen next to those which survived in Breezy Point, Queens.
Burned houses next to those that survived fires during Hurricane Sandy in Breezy Point, Queens.Adrees Latif/Reuters

But with Sandy, the storm surge, or rise in sea level, did some of the worst damage. It reached nearly 8 feet in parts of the Jersey Shore and 6 1/2 feet around New York City.

Its "superstorm" status was because it was so wide — up to 1,000 miles across.

Hurricane Katrina in 2005 was the most devastating storm ever to hit the US.

katrina floods streets and homes in an aerial view
Flooded neighborhoods seen as the Coast Guard conducted initial Hurricane Katrina damage-assessment overflights in 2005 in New Orleans.Getty Images

It killed 1,833 people and caused $108 billion in damage, though Katrina was technically a Category 3 when it made landfall in Louisiana with sustained wind speeds of 125 mph.

Category 4 hurricanes have wind speeds of 130 to 156 mph, uprooting most trees and creating power failures that can last weeks or even months.

homes are seen flattened from above from hurricane charley
Mobile homes seen torn apart north of Port Charlotte, Florida, on in 2004 after Hurricane Charley moved through the area.J.Pat Carter/AP

Hurricane Charley was a Category 4 when it made landfall in Florida in 2004.

Hurricane Maria was a Category 4 storm when it made landfall in Puerto Rico in 2017, leaving 100% of the island without power.

a woman holds on to a wooden pillar surrounded by floodwaters from hurricane maria
A woman tries to walks out from her house after the area was hit by Hurricane Maria in Salinas, Puerto Rico, September 21, 2017.REUTERS/Carlos Garcia Rawlins

Parts of the US commonwealth were still recovering from the hurricane two years later — 30,000 homes had tarps for roofs.

Hurricane Andrew was one of the strongest storms ever to make landfall in the US.

a water tower that says florida city is the only structure left standing in this aerial view of flattened buildings from hurricane andrew
The Florida City water tower remained standing over the ruins of the coastal community that was hit by Hurricane Andrew in 1992.AP

It was a Category 5 hurricane when it hit Florida's Dade County in August 1992.

Category 5 storms have wind speeds greater than 157 mph, which can destroy most framed homes, cause power failures, and leave areas where it hits uninhabitable for weeks or even months.

a blurry rainy TV live shot shows Barbuda flattened from Hurricane Irma
ABS News

Hurricane Irma was a Category 5 storm when it "totally demolished" the island of Barbuda in 2017.

During Irma, local weather stations in Barbuda captured wind gusts of 155 mph before going silent, indicating that the instruments had been blown away.

side-by-side nasa satellite images show the destruction from hurricane irma in barbuda
Satellite photos show Barbuda before and after Hurricane Irma devastated the island in 2017.NASA Earth Observatory

The destruction was so severe that the Caribbean island was initially cut off from communication, and 90% of its buildings were destroyed.

Hurricane Irma was so powerful that it could have been considered a Category 6 storm.

floodwaters cover streets and palm trees sway in Hurricane Irma's winds
Water rises up to a sidewalk by the Miami river as Hurricane Irma arrives at south Florida, in downtown Miami, Florida.Reuters/Carlos Barria

Theoretically, if we extended the Saffir-Simpson scale, Irma would be a Category 6, with wind speeds of 175 to 185 mph.

The problem with extending the Saffir-Simpson scale is that it's also a measurement based on destruction, and Category 5 storms typically destroy buildings and utilities.

2 rescue people in helmets stand in waist-high water around a submerged car during Hurricane Irma
Rescue staff from the Municipal Emergency Management Agency investigate an empty flooded car during the passage of Hurricane Irma through the northeastern part of Puerto Rico.AP Photo/Carlos Giusti

Technically, hurricanes above Category 5 wouldn't cause more damage because there's no more damage to be done.

Whether it's a tropical storm or a theoretical "Category 6", the impact for people in a hurricane's wake can be devastating.

a man comforts a distraught woman surveying a destroyed home after hurricane maria in puerto rico
A woman reacts while she looks at the damages in the house of her mother after the area was hit by Hurricane Maria in Guayama, Puerto Rico September 20, 2017.REUTERS/Carlos Garcia Rawlins

Part of the issue is that climate change is causing ocean and air temperatures to rise, which is making hurricanes more sluggish, giving them more time to suck up warm water and gain strength.

brightly colored satellite imagery shows Hurricane Dorian moving toward florida
The intensity of Hurricane Dorian as it sat over the Bahamas before it moved toward Florida.Tropical Tidbits

Read more: Tropical storms and hurricanes are getting stronger, slower, and wetter due to climate change

Read the original article on Business Insider