Hurricanes: How These Destructive Storms Form, and Why They Get So Strong

Five Categories of Mayhem

Hurricanes today are rated on the Saffir-Simpson scale, which places them into five categories according to wind speed. But the scale has been criticized for not accounting for rainfall totals, which can cause significant damage. Some atmospheric scientists have lobbied for a sixth category for even stronger storms, but there’s no official consensus on the idea.

Category 1 74-95 mph (Hurricane Isaac in 2012): Damage to roofs and windows. Shallow trees might be uprooted. Power outages are likely.

Category 2 96-110 (Hurricane Arthur in 2014): Flying debris poses a substantial risk to people and livestock. Mobile homes likely sustain heavy damage, and unreinforced masonry walls can tumble. Widespread power outages.

Category 3 111-129 (Hurricane Otto in 2016): Even well-built homes can suffer extensive damage, while older metal and brick buildings might topple. Most high-rise buildings will have shattered windows, and blackouts could last for weeks.

Category 4 130-156 (Hurricane Harvey in 2017): Very high risk from flying debris. Most mobile homes and poorly constructed homes will be destroyed, and even strong houses could lose roofs or walls. Trees will be snapped or uprooted, and power outages might last for weeks.

Category 5 157+ (Hurricane Maria in 2017): Significant number of houses and buildings destroyed. Windows will pretty much disappear; trees, signs and power poles annihilated; roofs will most likely be torn off. Power and water outages could last months.