Weather is always a crap shoot. That is the middle of hurricane season for the area. When they have landed there, many people who took their chances and stayed told dreadful stories - and even if a storm is hundreds of miles away it can make things rough. I went to Coz in late August for my birthday once with a major hurricane forecast to land, me thinking that surely it would veer off - but after a couple of days of it still closing directly on the island, I turned tail and got out as soon as possible. My trip insurance would have paid in full if I had canceled since a strike had been forecast and I could have kept the residuals from the plane ticket, etc - sweet, but I went and lost. Many in the group didn't take trip insurance then spent large amounts to buy escape tickets as well as losing the trip, but I did get out on a different airline at no extra charge. Hehe, there were many people arriving that day, asking why hundreds were standing in lines hoping to find seats: "What hurricane...?!"
Hits are rare though and I keep going back in late August as my odds of getting dives in are better than the more popular winter months. Get good trip insurance (I use TravelSafe.com), cancel if a direct hit is expected and get your money back for another trip, but you will probably not have any problems. Just check the forecasts daily, stay flexible in the adventure we call travel, and don't forget to check your connection cities the day before you fly. If weather is ever expected to be a problem, check with your airline, hotel and dive op about possible changes at no charge, as well as your insurance company to see if needed changes that require charges would be covered.
Cenotes are interesting diving but not for newbies in my opinion, and you still don't want to be in a hotel if a hurricane hits.
