May weather forecast
San Juan, PR

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

The last month of the spring, May, is another warm month in San Juan, Puerto Rico, with temperature in the range of an average high of 82.4°F (28°C) and an average low of 76.6°F (24.8°C).

Temperature

In San Juan, the average high-temperature in May is essentially the same as in April - a still warm 82.4°F (28°C). In San Juan, the average low-temperature is 76.6°F (24.8°C).

Heat index

In May, the average heat index is appraised at a tropical 89.4°F (31.9°C). Exhaustion is likely with prolonged exposure and activity. Sustaining activity may result in heat cramps.
Note that heat index values are valued for light wind and location in the shade. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel', 'apparent temperature', 'feels like', or 'felt air temperature', is an index that combines air temperature and relative humidity to determine the human-perceived temperature equivalent. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (pregnancy, metabolic differences, wind). Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

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

Rainfall

In San Juan, during 14.8 rainfall days, 1.06" (27mm) of precipitation is typically accumulated. Throughout the year, there are 159.9 rainfall days, and 12.01" (305mm) of precipitation is accumulated.

Ocean temperature

In San Juan, the average water temperature is 81.5°F (27.5°C).
Note: Water temperature between 77°F (25°C) and 84.2°F (29°C) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

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 in San Juan is 10.7h.

UV index

April through November, with an average maximum UV index of 7, are months with the highest UV index in San Juan. A UV Index reading of 6 to 7 represents a high health vulnerability from exposure to the Sun's UV radiation for the ordinary person.
Note: In May, the average maximum UV index of 7 translate into the following recommendations:
Take precautions against overexposure. Fair-skinned people may get burned in less than 20 minutes. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The strength of the UV rays is significantly increased by the reflection of the water and sand.
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FAQ

What is the temperature in May in San Juan?

In May, in San Juan, the average high-temperature is 82.4°F (28°C), and the average low-temperature is 76.6°F (24.8°C). In May, the average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which takes the relative humidity and factors it into the air temperature reading, is appraised at 89.4°F (31.9°C).

What are the most humid months in San Juan?

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

What is the average humidity in May in San Juan?

In May, the average relative humidity is 79%.

How many days does it rain in May in San Juan?

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

What is the ocean temperature in May in San Juan?

In May, the average ocean temperature in San Juan 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 San Juan?

In May, the average day length in San Juan, Puerto Rico, is 13h and 1min.

When are sunrise and sunset in May in San Juan?

In May, on the first day of the month, sunrise is at 5:56 am and sunset at 6:46 pm. On the last day of the month, in San Juan, Puerto Rico, 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 May, the average sunshine duration in San Juan is 10.7h.

What are the months with the highest UV index in San Juan?

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

What is the UV index reading in May in San Juan?

In San Juan, the average daily maximum UV index in May is 7. A UV Index value of 6 to 7 symbolizes a high hazard to health from exposure to Sun's UV rays.

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).

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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).

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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).

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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%).

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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").

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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).

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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).

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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 1min

The month with the longest days is June (Average daylight: 13h and 13min).
The month with the shortest days is December (Average daylight: 11h and 2min).

  • Average sunshine in May: 10h and 42min

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).

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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).

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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).

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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).

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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).

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