September is not the peak of the summer, but it still is hot, meaning temperatures of up to 35 degrees Celsius at mid-day at times. The norm is that it will cool down to 27-28 Degrees in the late evenings, early mornings down to 25 degrees, or even lower.
The most usual weather in the DR is partly cloudy with chance of short showers.
Other than the North Coast and the Northeast Coast, where it is not uncommon to have rainy days (it could rain for an hour), the South and Southeast and Eastern coasts will only get showers of about no more than 20 minutes and its over, and the sun will shine again. But even in the North and Northeast (the lushness of these regions is the payoff for all the rain), the rain is not much of a problem most of the year, so chances are that you will have excellent weather when you come.
