How is a hurricane category determined?

The Saffir-Simpson Hurricane Wind Scale is based solely on a storm's maximum 1-minute sustained wind speed. Category 1 starts at 74 mph and Category 5 begins at 157 mph. Since 2010 the official scale is wind-only and no longer formally includes pressure or surge.

What wind speed makes a Category 5 hurricane?

A Category 5 hurricane has maximum sustained winds of 157 mph (252 km/h) or higher. At this intensity a high percentage of framed homes are destroyed with total roof and wall failure, and the affected area can be uninhabitable for weeks to months.

What is the difference between a tropical storm and a hurricane?

A tropical storm has sustained winds of 39 to 73 mph and receives a name. Once sustained winds reach 74 mph it becomes a Category 1 hurricane. Below 39 mph the system is a tropical depression. All three can produce dangerous rain and flooding.

Does storm surge match the hurricane category?

Not reliably. Surge depends on the storm's size, forward speed, approach angle and the shape of the coastline, not just wind speed. A large Category 2 can push more water ashore than a small, compact Category 4, which is why surge was removed from the formal scale definition.

What is a major hurricane?

A major hurricane is Category 3 or higher, meaning sustained winds of at least 111 mph. These storms cause devastating to catastrophic damage and account for the large majority of hurricane-related deaths and economic losses in the United States.

Saffir-Simpson Hurricane Scale Reference

Email me this result

Get this tool's output sent to your inbox, plus one useful tool a week. No spam, unsubscribe any time.

Hurricane intensity from Category 1 to 5

This reference covers the Saffir-Simpson Hurricane Wind Scale, which rates hurricanes by their maximum sustained wind speed across five categories. It also lists the sub-hurricane tropical-depression and tropical-storm bands. Each entry shows wind speeds in mph and km/h, typical storm surge, and the damage to expect. A classifier converts any sustained wind speed into its category.

How it works

The official scale uses only the maximum 1-minute sustained wind speed. The classifier converts your input to mph first, then finds the band that contains it:

Tropical depression  <= 38 mph
Tropical storm       39 - 73 mph
Category 1           74 - 95 mph
Category 2           96 - 110 mph
Category 3           111 - 129 mph   (major hurricane)
Category 4           130 - 156 mph
Category 5           >= 157 mph

Knots are converted with mph = knots * 1.150779 and km/h with mph = km/h / 1.609344. Storm surge is shown as historical guidance only; the modern scale is wind-only.

Tips and notes

A “major hurricane” is Category 3 or stronger (111 mph and up).
Surge is driven by storm size and coastline, so do not judge flood risk by category alone.
The jump from Category 4 to 5 is small in wind speed but large in destruction because damage rises roughly with the cube of wind speed.
Inland flooding from rainfall kills more people than wind in many storms, regardless of category.