Does the category of a hurricane tell you how dangerous it is?

The category comes from the Saffir-Simpson scale, which rates a hurricane from 1 to 5 by its strongest sustained wind and nothing else.¹ For wind damage it's a useful guide, since the damage rises about fourfold with each step up the scale.² What the scale leaves out is storm surge, flooding from rain and tornadoes, and hurricanes of every category can bring all three.¹

Storm surge rises with the wind, but the storm's size and the sea floor off the coast matter too.³ A large storm's winds push on a wider stretch of ocean, and a wide, gently sloping sea floor lets that water pile higher.³ Hurricane Charley, a small storm, hit Florida as a Category 4 in 2004 and pushed up a surge of about 7 feet.² Four years later, Hurricane Ike was only a Category 2 when it reached Texas, but it was huge, and its surge rose to about 20 feet.²

Rain depends more on how big and slow the storm is than on how strong it is.⁴ Hurricane Florence came ashore in North Carolina in 2018 as a Category 1, but it moved so slowly that its rain bands kept passing over the same places.⁵ One spot got nearly 36 inches, and the flooding was devastating across much of the Southeast.⁵ Heavy rain like that can flood places hundreds of miles from the coast, and flooding is the main threat for people living inland.⁴⁶

So when a hurricane is coming, look past the number to the rain totals in the forecast, wherever you live. If you live where storm surge is a risk, find out whether your home is in one of the storm surge evacuation zones your local emergency managers set.⁷ If they tell you to leave, go, whatever the category.¹