The Caribbean dry season runs roughly December to April, and these are the busiest and most expensive months on Vieques. Days are dependably sunny, the trade winds keep the temperature down, and the bio bay is at its best as moonless nights are easier to find away from summer's rains.
May, June, and November are excellent shoulder months — lower prices, fewer crowds, and the rains, when they come, are typically afternoon showers. August to October is hurricane season; visit at this time with eyes open. The bio bay is brightest in the warmest months because the dinoflagellate populations peak.