If a storm is a Category 3, 4 or 5, it is deemed a "major" hurricane due to the potential for "significant loss of life and damage," the National Hurricane Center says. Hurricanes that fall into categories 1 or 2 are still considered dangerous, the center says.

The longstanding hurricane rating system, the Saffir-Simpson Scale, only takes into account sustained wind speeds and not the full devastating impact of a hurricane.

Hurricane Erin maintained its Category 2 strength early Wednesday morning as North Carolina's coasts prepared for life-threatening coastal flooding, with mandatory evacuations underway for some islands,

Let's break it down. Big Picture -What It Measures: As the name implies, the current version is strictly a wind scale that rates a hurricane's sustained winds (not gusts) from Category 1 through 5.

Erin, once a Category 5 hurricane over the weekend that more than doubled wind speed to nearly 160 mph, on Monday morning remained on a path to miss landfall of the United States though not without forcing evacuations in North Carolina.

Following a hurricane at a CATEGORY 4, most of an area will be “uninhabitable” for anywhere between weeks or months. CATEGORY 5: This is the highest category on the Saffir-Simpson wind scale.

In a study, Michael Wehner, PhD, and the Berkeley Lab found that the Saffir-Simpson Hurricane Wind Scale fails to tell the full story of higher wind speeds. "The strongest storms are getting stronger.

Hurricane Erin reached the maximum intensity on the Saffir-Simpson scale last Saturday (16), becoming a category 5 storm with winds of up to 260 km/h (161 mph).