What is a Cat 6 hurricane?

There is no such thing as a Category 6 hurricane. The Saffir-Simpson Hurricane Wind Scale only goes up to Category 5, which is defined as a hurricane with winds of 157 mph or higher. The scale was developed to classify hurricanes based on their wind speed, central pressure, and potential damage.

The categories are as follows:

Category 1: Winds of 74-95 mph (64-82 kt, 119-153 km/h)
Category 2: Winds of 96-110 mph (83-95 kt, 154-177 km/h)
Category 3: Winds of 111-129 mph (96-112 kt, 178-208 km/h)
Category 4: Winds of 130-156 mph (113-136 kt, 209-257 km/h)
Category 5: Winds of 157 mph or higher (137 kt or higher, 258 km/h or higher)

It's possible that you may be thinking of the Enhanced Fujita Scale, which is used to classify tornadoes, not hurricanes. The Enhanced Fujita Scale does have an EF5 category, which is the highest rating, but this is not related to hurricanes.

If you are interested in tracking hurricanes or staying informed about tropical weather, I recommend checking out the National Hurricane Center (NHC) or other reputable weather sources, such as the Weather Channel or AccuWeather.