A hurricane is just like any other low-pressure system.
But it gets bigger, and stronger, and picks up a lot of rain, by passing over warm, tropical ocean water.
If anything like climate change or hot fish were to come along and make that water warmer, then there would be more energy for the low pressure system to absorb from the warmer water. Then it would get even bigger and stronger, and it would pick up even more rain on its way over.
Also, normal-size low-pressure systems over the ocean that could never become tropical storms or hurricanes before, COULD do it now that the ocean is warmer. (Notice how this year, 2020, there have been so many hurricanes and tropical storms that NOAA ran out of names for them, and had to start using Greek letters. This has only happened once before.)