Whatever your plans, comfortable clothing is essential. Lightweight cottons and linens are advisable for day wear while light woolens are suggested for evenings. Try to avoid synthetic fabrics, which may not be as breathable as natural fibers.
Letting the cool Atlantic breeze blow through your clothing will go a long way toward keeping you comfortable in the tropical temperatures. Additionally, waterproof clothing and rain wear are a necessity all year long. Rain showers in Puerto Rico usually come up suddenly, come down hard, and end fairly quickly, so you need to be prepared with a waterproof jacket or umbrella. Opt for clothing that is easy to carry that you can quickly slip on and then put away again when the sun reappears.
If you're planning on visiting the mountain regions, you'll want to pack a jacket, sweater, or other warm attire, as the altitudes and cool breezes can make the mornings and evenings quite chilly. Don't forget comfortable shoes for walking, and sun glasses to prevent the sun from ruining your view.
Unlike Martinique or Jamaica, there are no nude beaches or resorts on Puerto Rico, but the island's social climate feels more like Latin America than the United States, so the atmosphere is very laid back. Swim wear is fine for the beach and leisurewear for the resorts, but elsewhere a little dressing up is in order. Nighttime in San Juan is somewhat informal, and nothing too fancy is required unless attending a formal event, visiting a casino, or dining in an upscale restaurant, but some common-sense clothing choices will keep you appropriate.
If you are traveling to the island for business, lightweight suits are appropriate business attire. The usual Western formalities and courtesies are observed in Puerto Rico. In the end, the best thing to do is to use common sense. If it wouldn't be appropriate where you live, it's probably safe to say Puerto Ricans would be uncomfortable seeing you wear it.
Pack light, pack smart, and pack for comfort, and you're sure to look great in Puerto Rico.
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