The islands have two main seasons the Dry Season, from January to May and the Wet or Rainy Season, from June to December.
In the Rainy Season, mornings are usually sunny, followed by rainy afternoons and fair nights. During this time, our general rainfall pattern is interrupted by days of brilliant sunshine; a climatic phenomenon we fondly call Petit Caręme. Petit Caręme is similar to what temperate climes know as Indian Summer and offers a warm, invigorating change from dull weather. This mini-break normally happens between mid September to mid October.
The Dry Season is mostly sunny, with occasional light showers. This is the weather that makes Trinidad and Tobago the perfect vacation spot.
Our islands share an average daytime temperature of 28 degrees Celsius that is warm but not unpleasantly humid and nights that are pleasantly cool.
Source : http://www.visittnt.com/