If you live near the coast, few words are scarier than these: Category Five. That’s the classification for the most powerful hurricanes. The storms have maximum sustained winds of at least 157 miles per hour. And their potential damage is catastrophic. They can flatten houses, bring massive storm surges, and cause heavy rainfall well inland.

In recent years, the most powerful tropical storms have been getting even stronger. And as our planet continues to warm up, they’re expected to get stronger still. So some scientists think it’s time to add even scarier words to the tropical-storm lexicon: Category Six. To qualify for this category, a storm would have wind speeds of at least 192 miles per hour.

A recent study found that five storms would have reached that threshold in the past nine years—four typhoons in the western Pacific Ocean, and one hurricane in the eastern Pacific—Hurricane Patricia. It hit the Pacific coast of Mexico with peak sustained winds of 215 miles per hour—the strongest storm yet recorded.

The study also projected that such monster storms will become more common in the years ahead. Climate change is making the oceans warmer, providing extra “fuel” to power typhoons and hurricanes. That may not increase the number of tropical storms, but it is expected to make the strongest of them even more intense. Some would even qualify for Category Six—a scarier name for the most powerful storms.