Katie and JZB are correct it not that its the peak of hurricane season, weather has nothing to do with it the weathers is fine. Its the fact the tourist in the US and Canada don't go on vacations in Sept. and the island is nearly a ghost town from lack of tourist.
Many business close rather than loose money trying to stay open. They go on vacation themselves. Were closing September 4th and reopen Oct. 1st as is Las Terrazas and many other hotels and diveshops.

White Sands Dive Shop
https://whitesandsdiveshop.com/