We have been in mid January. Diving is still ok, but not at its best IMO. Visibility was down, due to rain and runoff. Our logs show most visibility was 50 feet to 80 feet depending on the rain situation. The water temp. was ok (77-78 degreees, per our logs) while you were diving (understand though that we refuse to wear wetsuits) but when we came up we were cold (it was windy and overcast a lot). Short rain shower every day and the ground was constantly damp, which was an advantage as it kept the sand packed down. Cold water upwellings from the trenches brought out a lot of sea wasps at night dives. If you night dive, wear a wetsuit or a skin. We found out the hard way.......
All in all we were glad to get away to a warmer climate, but it would have been nice to be a little warmer and have a little more visibility.