May weather forecast
San Juan, PR

May in San Juan heralds the arrival of the city's warmest period. The average high temperature escalates to 82.4°F (28°C), as does the sea temperature, reaching 81.5°F (27.5°C). Notably, the month has the year's maximum rainfall of 1.06" (27mm). Coincidentally, daylight and sunshine hours peak, paving the way for longer, warmer days amidst the tropical rain. The rise in warmth and precipitation establishes the onset of San Juan's summer.

Temperature

San Juan's average high-temperature marks a still moderately hot 82.4°F (28°C) with the advent of May, closely mirroring that of the preceding month. May nights anticipate an average temperature of 76.6°F (24.8°C), a modest decline from the daytime.

Heat index

May's heat index is estimated at a hot 89.6°F (32°C). If one endures exposure and continues to be active, it might result in tiredness and heat cramps.
When referencing the heat index, its values are suitable for shady environments and light breezes. If exposed to direct sunlight, the heat index could climb by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', is a measure that combines air temperature and relative humidity into a single value that indicates how hot the weather feels. Factors including metabolic differences, physical activity, and clothing are additional elements that influence the individual's temperature experience. Keep in mind that direct sunshine exposure can amplify the weather's effects, possibly increasing the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are quite important for children. Young children typically face greater hazards than adults because they do not sweat as much. Their larger skin surface in comparison to their little bodies and the high heat production from their active nature compounds their vulnerability.

Humidity

May through July, with an average relative humidity of 79%, are the most humid months.

Rainfall

In May, the rain falls for 14.8 days. Throughout May, 1.06" (27mm) of precipitation is accumulated. In San Juan, during the entire year, the rain falls for 159.9 days and collects up to 12.01" (305mm) of precipitation.

Ocean temperature

In San Juan, in May, the average water temperature is 81.5°F (27.5°C).
Note: Water temperature ranging from 77°F (25°C) to 84.2°F (29°C) is recognized as warm and pleasant by all, making water activities comfortable and delightful for long durations.

Daylight

In San Juan, the average length of the day in May is 13h and 1min.
On the first day of May, sunrise is at 5:56 am and sunset at 6:46 pm. On the last day of the month, sunrise is at 5:47 am and sunset at 6:57 pm AST.

Sunshine

In May, the average sunshine is 10.7h.

UV index

April through November, with an average maximum UV index of 7, are months with the highest UV index. A UV Index reading of 6 to 7 represents a high health vulnerability from unsafe exposure to UV radiation for average individuals.
Note: A typical high UV index of 7 in May suggests the following recommendations:
Stick with precautions and abide by sun safety procedures. Evading sunburn is essential. Stay in the shade and avoid direct Sun exposure from 10 a.m. to 4 p.m., a time when UV radiation is at its strongest, and remember that parasols or canopies do not offer full protection. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days. Stay vigilant! UV rays get a boost in intensity due to sand and water reflections.