November in general is not a good month for the Gulf islands. Even if last year was 'good', chances are you do get washed out. I live on Koh Samui and my advice is to not take the chance and if you're in Thailand, head for the other side, the Andaman coast, Statistically a much higher chance of better weather and dive conditions there during November.
Plenty of options with Koh Lanta and Khao Lak for starters.
Plenty of options with Koh Lanta and Khao Lak for starters.