IMHO heat would only make things worse. I was just sitting in the car on the way home calculating the energy avaliable in the Gulf. If you lower one pound of water by one degree farenheit, that releases one BTU of energy. Figure just how many pounds of water there are in the top foot or so of the water under the hurricane, measure the temperature change, multiply the BTUs per minute by 0.0235809 to get horsepower (or 0.0175843 to get Kilowatts, if you prefer) and that's a staggering release of energy.
A nuke is a pop gun by comparison- it releases a LOT of energy, but in a thousandth of a second. The hurricane is generating this power continuously.
You could have every plane in the air force dropping dry ice and cryogenic liquids, and it wouldn't make enough difference to matter.
You are right, heat is what fuels these things.