Both suggestions above are great.
I would not worry about the weather too much, it is what it is.
Flying into Roatan is great but when I went in May it was $700, from Chicago so I flew into San Pedro Sula for $289 on United/Continental via Houston.
SPS is not worth much, I arrived at 1pm and bought a ticket at the airport to Roatan departing at 330, stopping in La Cieba for 20 minutes or so, had to change planes from a 20 seater to a 10 seater...if you arrive later, you can take the Pullman bus to La Ceiba and stay there a night and then take ferry to Utila and Roatan. In SPS a good place downtown on the plaza is the Gran Sula, about $55 with a pool and free breakfast.
I stayed 4 nights on Roatan, and 4 nights on Utila, and took Verns catamaran between them $55. I liked both, but Roatan to me had easier access, and was closer to the good diving, just minutes by boat to many great dive sites. Roatan is a tad more laid back and less going on, compared to Utila, which everything is mainly condensed on the main drag, a little noisy and too much moto traffic for me. Though Altons and Lighthouse is past all the action and much more peaceful at that end.
In Roatan I stayed in a cottage just outside of town, at Blennys House. I spent 2 days diving, first day a refresher course and 2 dives, then next day 4 dives including a night dive..
On Utila, I stayed at the UDC Mango Inn, and took the 2 day Advanced course, and also had 4 additional dives. You may just want to get your OW and Advanced, and then your pretty much good to go for most your life diving needs. I found all the dive operations very professional and seemed everyone was having a good time and learning everything from great DM's. It is really a good atmosphere on both islands to dive, and NOv you will have fewer people in the class most likely, and more attention, even though UDC was excellent with 12 people in the Advanced class.
Enjoy,
Its all good...