May weather forecast
San Juan, PR

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An old fort building and a view of the stunning San Juan city, Puerto Rico
An old fort building and a view of the stunning San Juan city, Puerto Rico

Weather in May

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.

Frequently asked questions

Is it hot during May?

The high-temperature, in May, in San Juan, records 82.4°F (28°C), while the low-temperature is 76.6°F (24.8°C). In May, the average heat index (a.k.a. 'feels like', 'apparent temperature'), which combines air temperature and relative humidity, is estimated at 89.6°F (32°C).

What are the most humid months?

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

What is the average humidity in May?

The average relative humidity in May is 79%.

How much does it rain in May?

In San Juan, in May, it is raining for 14.8 days, with typically 1.06" (27mm) of accumulated precipitation.

How warm is the water in May?

In May, the average ocean temperature is 81.5°F (27.5°C). For swimming, diving, and other water activities, temperatures between 77°F (25°C) and 84.2°F (29°C) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

What is the average length of the day in May?

In May, the average day length is 13h and 1min.

What time are sunrise and sunset in May?

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.

How many hours of sunshine does San Juan have in May?

In San Juan, Puerto Rico, the average sunshine duration in May is 10.7h.

What are the months with the highest UV index?

April through November, with an average maximum UV index of 7, are months with the highest UV index.

How high is the UV index in May?

In San Juan, the average daily maximum UV index in May is 7. A UV Index reading of 6 to 7 represents a high health threat from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in May
San Juan, PR

Average temperature in May - San Juan, PR
  • Average high temperature in May: 82.4°F

The warmest month (with the highest average high temperature) is August (85.1°F).
The months with the lowest average high temperature are January and March (79.9°F).

  • Average low temperature in May: 76.6°F

The months with the highest average low temperature are August, September and October (79.2°F).
The coldest month (with the lowest average low temperature) is March (73.9°F).

Average pressure in May
San Juan, PR

Average pressure in May - San Juan, PR
  • Average pressure in May: 29.98"Hg

The months with the highest atmospheric pressure are January and February (30.02"Hg).
The month with the lowest atmospheric pressure is October (29.9"Hg).

Average wind speed in May
San Juan, PR

Average wind speed in May - San Juan, PR
  • Average wind speed in May: 9.1mph

The windiest month (with the highest average wind speed) is July (10.7mph).
The calmest month (with the lowest average wind speed) is October (7.4mph).

Average humidity in May
San Juan, PR

Average humidity in May - San Juan, PR
  • Average humidity in May: 79%

The months with the highest relative humidity are May, June and July (79%).
The months with the lowest relative humidity are February and March (76%).

Average rainfall in May
San Juan, PR

Average rainfall in May - San Juan, PR
  • Average rainfall in May: 1.06"

The wettest month (with the highest rainfall) is November (1.57").
The driest month (with the least rainfall) is April (0.55").

Average rainfall days in May
San Juan, PR

Average rainfall days in May - San Juan, PR
  • Average rainfall days in May: 14.8 days

The month with the highest number of rainy days is November (16.1 days).
The month with the least rainy days is June (10.3 days).

Average sea temperature in May
San Juan, PR

Average sea temperature in May - San Juan, PR
  • Average sea temperature in May: 81.5°F

The best month for swimming (with the highest average sea temperature) is September (84.9°F).
The coldest month (with the lowest average sea temperature) is February (78.9°F).

Average daylight in May /
Average sunshine in May
San Juan, PR

Average daylight in May / Average sunshine in May - San Juan, PR
  • Average daylight in May: 13h and 0min

The month with the longest days is June (Average daylight: 13h and 12min).
The month with the shortest days is December (Average daylight: 11h and 0min).

  • Average sunshine in May: 10h and 4min

The month with the most sunshine is June (Average sunshine: 10h and 54min).
The month with the least sunshine is December (Average sunshine: 6h and 36min).

Average sunshine days in May
San Juan, PR

Average sunshine days in May - San Juan, PR
  • Average sunshine days in May: 10.9 days

The month with the most sunshine days is June (13.7 days).
The month with the least sunshine days is November (9.4 days).

Average UV index in May
San Juan, PR

Average UV index in May - San Juan, PR
  • Average UV index in May: 7

The months with the highest UV index are April, May, June, July, August, September, October and November (UV index 7).
The months with the lowest UV index are January, February, March and December (UV index 6).

Average cloud cover in May
San Juan, PR

Average cloud cover in May - San Juan, PR
  • Average cloud cover in May: 34

The month with the most cloud cover is December (Cloud cover 35).
The month with the least cloud cover is September (Cloud cover 26).

Average visibility in May
San Juan, PR

Average visibility in May - San Juan, PR
  • Average visibility in May: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

San Juan, Puerto Rico, USA

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