https://motherboard.vice.com/en_us/article/nembvm/hurricane-categories-dont-capture-how-dangerous-florence-is

By the time Hurricane Florence made landfall this morning, it had been downgraded from a Category 4 storm to a Category 1. Although this is good news, the storm is still dangerous and shouldn’t make you complacent. A Category 1 storm can still be devastating, because the scale we use to categorize storms only takes into account one factor—wind speed—and when it comes to hurricanes there are many other factors to worry about.

The categories we give to hurricanes are based on the Saffir-Simpson Hurricane Wind Scale, which was developed in the 1970s as a way to simply communicate a hurricane’s intensity. Each category (1-5) is determined exclusively by wind speed—a category 3 hurricane, for example, has wind speeds between 111 and 129 miles per hour.