On Tuesday, Hurricane Irma—currently the strongest Atlantic hurricane ever recorded outside the Caribbean Sea or Gulf of Mexico—hit wind speeds of 185mph, the Baltimore Sun reports. And scientists are split on whether it's even possible for a hurricane to get much stronger. According to Live Science, warm water makes hurricanes stronger, and warming oceans due to climate change could theoretically create ever-stronger hurricanes. For example, NOAA states human-caused global warming could increase hurricane strength by 2% to 11% by the end of the 21st century. And some scientists say wind speeds will increase by about 5% for every degree Celsius increase in ocean temperature. Others disagree; a meteorologist at the National Hurricane Center says hurricane winds are unlikely ever to top 200mph. In 1998, scientists calculated maximum hurricane wind speeds of 190mph based on current environmental conditions.
But regardless of how strong their winds can or will get, no hurricane will ever be stronger than a Category 5. That's because the Saffir-Simpson scale has no Category 6. A Category 5 hurricane is one that has wind speeds of 156mph or more. Robert Simpson says he didn't go higher than Category 5 when creating the scale because at that point potential damage is all the same. “At 5 ... you already have catastrophic damage,” Dennis Feltgen at the National Hurricane Center tells WDBO. “It’s done.” (Read more hurricane stories.)