I seem to recall something about hurricane strength being strongly related to the temperature deep under the ocean. Surface temperature didn't make much of a difference; a strong hurricane was more the result of a large sink of warm water. You can have a warm surface that gets cold quickly underneath, meaning there isn't much total energy there for the hurricane to draw from. Meanwhile, a cooler but deeper layer of warm water contains more energy, resulting in stronger winds.

*does some searching*

I wish I could find the link to the video of this guy on CNN. He had a good explanation of it. He also seemed quite neutral to the global warming question as it pertained to hurricane strength (almost dismissive of the idea, though the interviewer clearly wanted to hear something about global warming).

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