We stayed in Punta Cana from 29th January for 2 weeks last year. The first week we had great weather then it rained for the next 5 days and nights. It was a bit hard to find enough to keep us occupied with such a long period of rain other than eat and drink!!
If you have booked to go on a trip and the weather is bad they still go, you dont get a refund. We did the safari in the pouring rain with the truck covered in plastic and all the diesel fumes coming in, yuck!
the weather cleared up for our last day and a half. The locals said this was very unusual weather for the time of the year It was the weel that we had heavy snow here in the UK.
I guess the weather is the one thing you have to take pot luck on wherever you go.