I was told that the cruise ships reroute rather than cancel for Hurricanes. Only been on two cruises and this year we are doing our 3rd in the Pacific. I would go, too, in February but the rates are high then. The best time is near the end of Hurricane season to balance rates against weather.
But, you mentioned Carnival. They usually have excellent rates but the people density on their ships are slightly higher and lately they have suffered some bad press with a poor trackrecord for food poisoning. I'm on their e-mail list and everytime they have bad press, they announce reduced rates. Isn't HT cruises with David Bott doing their cruise on Carnival this year?
Anyway, I'm going mid October to west coast of Mexico on Princess cruises. I hope the Hurricane season should be over by then. Early start usually means an early end to the season.