Average high temperature and rainfall for San Juan in May. © Scott S. Bateman

San Juan weather in May is both warmer and wetter than the dry season that goes from January through April.

The San Juan cruise port in Puerto Rico is one of the most popular ports in the Caribbean because of its central location. It’s a frequent port of call for eastern Caribbean cruises and a starting point for southern Caribbean cruises.

But San Juan’s weather in May is not ideal for cruise or hotel visitors.

San Juan Temperatures in May

Temperatures are certainly warm enough for anyone who likes water activities or spending time at the beach.

San Juan’s temperatures in May have an average daytime high of 87 degrees Fahrenheit or nearly 31 Celsius, according to the U.S. National Weather Service. Nighttime temperatures average 75 degrees Fahrenheit or nearly 24 Celsius.

By comparison, daytime temperatures range from an average of 83 degrees Fahrenheit in January to 85 Fahrenheit in April. They keep increasing to about 89 degrees Fahrenheit or 32 Celsius in the summer months. So May is just above average for the entire year.

Water temperatures are almost always comfortable for swimming in May, even in the mornings and despite trade winds. The same isn’t true for San Juan water temperatures during the dry season, especially in January and February. They will often feel chilly in the mornings, especially if there are strong trade winds.

Rainy Season in May

San Juan has a brief rainy season in May that comes after the dry season from January through April. During the dry season, total rainfall averages less than three inches a month. In May, rainfall in San Juan jumps to six inches, according to the U.S. National Weather Service.

How often it rains also takes a jump. The average goes from about eight days in March and April—the lowest of the year—to nearly 13 days in May.

San Juan weather in May is not ideal for cruise and resort visitors. Anyone with flexible travel schedules should consider going to San Juan in March or especially April when the risk of rain is much lower. Temperatures are slightly cooler then, but they more than make up for the brief rainy season in May.

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