Hurricane Helene made landfall near Perry, Florida, as a Category 4 storm with sustained winds of 140 mph and stronger gusts.

It is the strongest hurricane ever to hit Florida’s Big Bend. Its fierce winds and heavy rains could cause widespread power outages and flooding in the southeast, where the ground is already saturated from the previous day’s storms.

But what do these categories mean?

Hurricanes are rated 1 to 5 on the Saffir-Simpson Hurricane Wind Scale based on their wind speed. Damage increases exponentially as wind speed increases, meaning a strong Category 3 storm can cause up to 60 times as much damage as a weak Category 1 storm.

Here are the main risks you can expect in each category:

Category 1: 74-95 mph

Sustained wind is enough to blow away shingles and damage gutters and vinyl siding. These winds can also uproot trees and down branches, causing power outages and further property damage. They can also damage power lines.

Category 2: 96-110 mph

Winds this strong can cause up to 20 times more damage than a Category 1 storm, including significant damage to the roof and siding of a home.

Most likely, numerous trees and power lines will be damaged, blocking roads, damaging property and knocking out power for days, if not weeks.

Category 3: 111-129 mph

Now wind damage is much more widespread in the “severe hurricane” area. Well-built homes and other buildings could suffer extensive damage, and roofs will suffer severe damage. Numerous trees are damaged or uprooted. Electricity and water could be cut off for several days.

Category 4: 130-156 mph

These winds can cause catastrophic damage. Well-built homes suffer severe damage, with most of the roof blowing off. Trees and power lines will fall. Water and electricity supplies could be out for months and the hardest-hit areas could be uninhabitable for weeks.

Category 5: 157 mph or more

These are the strongest storms on Earth. Most well-built houses are destroyed and many are destroyed to the ground. Power outages could last for months and the hardest hit areas could be uninhabitable for months.