Spoke to the Coral Caribe by Hilton in Juan Dolio (
http://dr1.com/directories/hotels/coral_caribe.shtml). Their report is that it is very sunny, didn't rain yesterday, and rain is not expected for today.
Regarding weather in Juan Dolio, it is much drier than Santo Domingo, and even La Romana.
Check back closer to your date of departure, as very rarely are five-day or even two day forecasts accurate in the Caribbean, outside of the general observation for weather that we make in our
http://www.dr1.com/travel/expect/weather.shtml page.