How strong can hurricanes get?

Hurricane Milton, which is expected to make landfall on the Florida coast Wednesday or early Thursday (Oct. 9 or 10), seemed to come out of nowhere: Just a tropical storm on Sunday, the hurricane roared into the Category 5 range Monday (Oct. 7), with sustained winds of 180 mph (298 km/h) before weakening slightly on Tuesday (Oct. 8).

But how close is Milton's sustained wind speed to the theoretical maximum? And is there a hard limit?

There is a "speed limit," on sustained wind speed, called maximum potential intensity, but it is not absolute: It is dictated by several factors, including the heat present in the ocean. Current calculations of the maximum potential intensity for storms typically peaks around 200 mph (134 km/hour).

But that may change in the coming decades as oceans warm and the climate changes. Already, the potential for strong storms has been rising over the past 30 years, said Kerry Emanuel, an emeritus professor of atmospheric Science at MIT who developed the model. So have actual monster storms: Five storms on record have had winds exceeding 192 mph (309 km/hour). All of those have occurred since 2013.

"I think by the end of the century, if we don't do a lot of curbing, it's going to be closer to 220 [mph]," Emanuel told Live Science.

Related: We may need a new 'Category 6' hurricane level for winds over 192 mph, study suggests

What drives a storm

The speed limit on hurricane winds is relatively easy to calculate, said James Kossin, a climate scientist who is retired from the National Oceanic and Atmospheric Administration (NOAA) and now consults for the climate risk modeling agency First Street.