For a sunset sailing and snorkeling experience in Aruba, January through August are usually the strongest months. During this period, it is often more pleasant to plan an evening on the water, with steadier conditions for a relaxed trip and a better chance of an easy, enjoyable experience.
Why these months work well: - the evenings are usually pleasant for being outside - a sunset cruise feels especially natural as a way to end the day - snorkeling and sailing fit well with a calm, dry travel plan
Outside this window, the experience can still be worthwhile, but it makes sense to allow a bit more room for changing weather, availability and flexibility in your planning. If you are travelling in the rainy season, it is wise to leave some space in your schedule.