Hurricane Irma, which has killed at least 20 people in the Caribbean and is expected to begin affecting southern Florida Saturday night, is one of the most powerful Atlantic hurricanes ever recorded. Its strongest winds reached speeds of 185 miles per hour and stayed there for 37 hours. Hurricane Allen is the only Atlantic hurricane that has clocked faster wind speeds — though three others have tied Irma — and no cyclone that humans have measured anywhere on the planet has ever sustained such speeds for so long.

Currently a Category 4 hurricane, Irma is likely to remain that strong when it reaches the continental U.S. Its projected course takes it right into the southern tip of Florida, the same area where many of the strongest hurricanes that have hit the southeastern U.S. have made landfall. At least nine Category 4 or 5 hurricanes have made landfall in Florida since 1898.

And what lies in that path? We can’t say for sure, but within the so-called cone of uncertainty for Irma, there are 11 nuclear power plants, hundreds of hospitals and a slew of hazardous waste containment sites that could become sources of environmental contamination.

Another thing to look out for: an immense amount of building damage in Florida. According to the insurance company Swiss Re, if a hurricane like 1992’s Category 5 Andrew were to hit south Florida today in exactly the same spot, it would create up to $100 billion in damage upfront, as opposed to the $27 billion ($48 billion in 2017 dollars) in losses it caused at the time.

Read more: “The Worst Case Scenario For Hurricane Irma Looks Likely”