General info about Vieques weather:
Vieques climate is tropical-marine with temperatures that average about 79 degrees Fahrenheit. Annually, the temperature ranges from an average of 76 degrees Fahrenheit in February to 82 degrees Fahrenheit in August. Vieques lies in the path of the easterly trade winds, which regulate the rainfall on the island. The average amount of precipitation is about 45 inches a year. The western part of the island receives a higher amount of rainfall (about 50 inches a year) than the eastern section (about 25 inches a year). The rainy season is from August through November while the remainder of the year is drier. Tropical storms are common from June to November. (National Climatic Data Center, 1994. Annual Climatological Summary for Vieques Island, Puerto Rico: May 1985 through January 1994, and Torres-Gonzalez S., 1989. Reconnaissance of the ground-water resources of Vieques Island, Puerto Rico. U.S. Geological Survey, Report 86-4100. San Juan, P.R.:1989. As published in the U.S. Department of Health Public Health Assessment for Isla de Vieques Bombing Range February 20, 2001).
Tide Tables 2013