Hurricane Ian hit Florida as a Category 4 storm on Wednesday afternoon, bringing very high winds and storm surges. With the massive storm making landfall as a Category 4 hurricane, it could stand as one of the strongest storms to ever hit the U.S. mainland.
There are a few ways to rate the severity of a storm when trying to define the "worst" or "biggest" -- wind speed, lowest internal pressure and damage costs. In 2018, Hurricane Michael hit Northwest Florida as the third most intense storm to ever reach the U.S. The National Oceanic and Atmospheric Administration said the storm's pressure was 919 millibars (MB).
Here are the 10 most intense hurricanes in U.S. history, as measured by central pressure, according to the National Oceanic and Atmospheric Administration. The lower the pressure, the more intense the storm.
1. Florida (Keys) - 1935, 892 mb
2. Camille (Mississippi, Louisiana, Virginia) - 1965, 900 mb
3. Michael (Florida) - 2018, 919 mb
4. Katrina (Louisiana) - 2005, 920 mb
5. Andrew (Florida, Louisiana) - 1992, 922 mb
6. Texas (Indianola) - 1884, 925 mb
7. Florida (Keys) - 1919, 927 mb
8. Florida (Lake Okeechobee) - 1928, 929 mb
9. Donna (Florida) - 1960, 930 mb
10. Carla (Texas) - 1961, 931 mbData is current through 2021

Hurricane Katrina, which decimated New Orleans in 2005, is essentially tied with Michael as the third most intense to make U.S. landfall, but was by far the costlier storm. According to NOAA, Katrina, which hit the Bahamas, Florida, Louisiana, Mississippi and Alabama, resulted in $40.6 billion in insured losses and more than $108 billion in total estimated losses.
A vast majority of the 10 costliest hurricanes to hit the U.S. mainland have occurred since 2005, the NOAA said.
10 costliest hurricanes in the U.S. from 1900-2017, adjusted to the 2022 U.S. dollar
1. Katrina (2005) - $188.5 billion
2. Harvey (2017) - $150.79 billion
3. Sandy (2012) - $83.22 billion
4. Irma (2017) - $60 billion
5. Andrew (1992) - $56.75 billion
6. Ike (2008) - $40.61 billion
7. Ivan (2004) - $31.97 billion
8. Wilma (2005) - $28.25 billion
9. Rita (2005) - $27.56 billion
10. Charley (2004) - $25.01 billion

And these are the 10 deadliest hurricanes in U.S. history to hit the mainland
1. Texas (Galveston) 1900, 8,000-12,000 casualties
2. Florida (SE/Lake Okeechobee) 1928, 2,500-3,000 casualties
3. Katrina (Louisiana, Mississippi, Alabama, Florida, Georgia) - 2005, 1,500 casualties
4. Louisiana (Cheniere Caminanda)- 1893, 1,100-1,400 casualties
5. South Carolina/Georgia (Sea Island) - 1893, 1,000-2,000 casualties
6. Georgia/South Carolina - 1881, 700 casualties
7. Audrey (Louisiana, Texas) - 1957, 416 casualties
8. Florida (Keys) - 1935, 408 casualties
9. Louisiana (Last Island) - 1856, 400 casualties
10. Florida (Miami) - 1926, 372 casualties
Data current through 2013. Some figures are estimated.

If hurricanes outside the continental U.S. are factored in, two hurricanes to strike Puerto Rico - San Felipe (1928) and David (1979) - rank among the most intense in history. And Hurricane Maria, which struck Puerto Rico in 2017, decimated the island, causing an estimated $90 billion in damage and left nearly 3,000 people dead.
According to the NOAA, several 19th century hurricanes to strike Puerto Rico and one in 1928 (San Felipe) and 1932 (unnamed), would rank among the 20 deadliest storms.
Another notable record for hurricanes, while not in the U.S., includes record storm surge. NOAA says Tropical Cyclone Mahina struck Australia in 1899 and produced a storm surge of 30 feet.
The largest hurricane death toll on record is the Bangladesh Cyclone of 1970, an estimated 500,000 people died due to the storm surge, according to the National Weather Service.