As Hurricane Milton barrels toward Florida and threatens devastating damage, the storm's ever-changing wind speeds have likely left many wondering what exactly determines a hurricane's category.

Milton, previously a Category 5 storm, has weakened to Category 3 as it approaches landfall near the Tampa Bay area, which could land a one-time direct hit on Tampa and St. Petersburg.

Since changing wind speeds cause the category of a given storm to fluctuate, many wonder what causes a storm to be placed in a particular category.

Here's a look at the hurricane categories and how they work:

What are the hurricane categories?

The hurricane categories are based on the so-called Saffir-Simpson hurricane wind scale.

The rating categorizes hurricanes on a scale of 1 to 5 based on sustained wind speed, according to the National Weather Service.

“This scale estimates potential property damage,” the NWS reports. “Category 3 and above hurricanes are considered major hurricanes due to their potential for significant loss of life and damage. However, Category 1 and 2 storms are still dangerous and require preventive measures.”

Wind speeds are calculated using a one-minute average.

This is how they break down:

According to the scale, in a category five storm, “a high percentage of frame houses will be destroyed, with complete roof failure and wall collapse.”

“Fallen trees and utility poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months,” the description reads.

Is there a category 6?

Earlier this year, some experts suggested adding a Category 6 to the rankings for storms with winds of more than 192 miles per hour, although such a category has not yet been officially created.

Several experts told The Associated Press that they do not believe this category is necessary. They said it could even send a false signal to the public because it is based on wind speed, when water is by far the deadliest cause of death in hurricanes.

What causes a hurricane?

A hurricane is a tropical cyclone with maximum sustained winds of 74 miles per hour or greater, usually assigned to category 1 or 2 on the Saffir-Simpson hurricane wind scale.

“Hurricanes are powerful weather events that extract heat from tropical waters to fuel their fury. These intense storms form over the ocean and often begin as a tropical wave — an area of ​​low pressure that moves through the moisture-rich tropics, potentially increasing showers and thunderstorms As the tropics move, warm ocean air rises into the storm and forms a low pressure area underneath. This causes more air to flow in. The air then rises and cools, causing clouds and thunderstorms to form. Water condenses and forms droplets more heat is released, fueling the storm.

A Category 1 storm has sustained wind speeds between 74 mph and 95 mph, and a Category 2 storm is between 96 mph and 110 mph.

A major hurricane is a tropical cyclone with maximum sustained winds of 111 miles per hour or greater, classified as Category 3, 4, or 5.