Appendix A: Regional Summaries, Caribbean.
The United States Caribbean is an insular territory composed of a rich mix of the principal inhabited islands of Puerto Rico (including Vieques and Culebra) and the United States Virgin Islands (St. Croix, St. Thomas, St. John, and Water Island), over 800 smaller islands, and cays. It is a region of tropical humid and semiarid mountains, valleys, and coastal plains with a climate strongly influenced by the surrounding ocean. The rainfall distribution pattern on the islands surrounding the Caribbean is much more even than on most land areas within the Tropics (Ewel and Whitmore 1973). Yet precipitation in the United States Caribbean is mostly bimodal with an initial maximum around May, a relative minimum in June–August, and a second peak in September–October (Chen and Taylor 2002; Giannini et al. 2000; Rudloff 1981). Most of the precipitation in the region is orographic, given the diverse topography of the larger islands.