San Juan
Puerto Rico, USA
Long-term weather forecast
Long-term weather forecast

August weather forecast and climate
San Juan, PR

An old fort building and a view of the stunning San Juan city, Puerto Rico, with a clear view of the calm waterfront
An old fort building and a view of the stunning San Juan city, Puerto Rico, with a clear view of the calm waterfront
The last month of the summer, August, is another hot month in San Juan, Puerto Rico, with average temperature ranging between min 78.3°F (25.7°C) and max 89.2°F (31.8°C).

Temperature

August and September, with an average high-temperature of 89.2°F (31.8°C), are the warmest months.

Heat index

The average heat index in August is calculated to a blistering 108°F (42.2°C). Beware - heat cramps and heat exhaustion are very likely. Heatstroke is imminent with prolonged activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With the exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel', 'apparent temperature', 'felt air temperature', or 'feels like', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. This effect is individual, with diverse people perceiving weather differently for numerous reasons (differences in body mass, height, and shape, clothing, wind), and activity. Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. 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.
The human body cools itself through perspiration, as excessive warmth is removed from the body through sweat evaporation. A higher relative humidity affects normal body cooling by reducing the evaporation rate, subsequently lowering the rate at which the body cools and increasing the perception of heat. If the body can not disperse the excessive heat and body temperature reaches conditions of hyperthermia, above 99.5°F (37.5°C) to 100.9°F (38.3°C), thermal conditions are potentially life-threatening.

Humidity

The average relative humidity is 76.4%.

Rainfall

The month with the most rainfall is August when the rain falls for 18.5 days and typically aggregates up to 7.7" (195mm) of precipitation.

Ocean temperature

In August, the average ocean temperature is 84.6°F (29.2°C).
Note: 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.

Daylight

In San Juan, the average length of the day in August is 12.7h.

Sunshine

The average sunshine in August is 8.6h.

UV index

March through September, with an average maximum UV index of 12, are months with the highest UV index in San Juan, Puerto Rico. A UV Index value of 11, and more, symbolizes an extreme health hazard from the exposure to the Sun's UV radiation for the ordinary person.
Note: The average daily UV index of 12 in August transform into the following instructions:
Practice all-important precautions. Light skin people may get burned in less than 5 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. Even on cloudy days, a sunscreen with a minimum 30 sun protection factor should be generously applied and frequently re-applied, including after every swim or outdoor exercise. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.

What are the warmest months in San Juan?

August and September, with an average high-temperature of 89.2°F (31.8°C), are warmest months.

What is the temperature in August in San Juan?

In August, the average high-temperature is 89.2°F (31.8°C), and the average low-temperature is 78.3°F (25.7°C). The average heat index (a.k.a. 'real feel', 'apparent temperature'), that combines relative humidity and air temperature, in August is calculated to 108°F (42.2°C).

What is the average humidity in August in San Juan?

In San Juan, the average relative humidity in August is 76.4%.

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

In San Juan, Puerto Rico, in August, during 18.5 rainfall days, 7.7" (195mm) of precipitation is typically accumulated.

What is the rainiest month in San Juan?

August is the month with the most rainfall in San Juan, Puerto Rico. Rain falls for 18.5 days and accumulates 7.7" (195mm) of precipitation.

What is the water temperature in August in San Juan?

In August, the average ocean temperature in San Juan, Puerto Rico, is 84.6°F (29.2°C). 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.

How many hours of daylight does San Juan have in August?

In August, the average length of the day in San Juan, Puerto Rico, is 12.7h.

How long on average sun shines in August in San Juan?

In San Juan, the average sunshine in August is 8.6h.

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

Months with the highest UV index in San Juan, Puerto Rico, are March through September, with an average maximum UV index of 12.

What is the UV index intensity in August in San Juan?

The average daily maximum UV index in August in San Juan, Puerto Rico, is 12. A UV Index estimate of 11, and higher, represents an excessive health risk from the exposure to the Sun's UV rays.
Average temperature in August - San Juan, PR
  • Average high temperature in August: 89.2°F

Warmest months (with the highest average high temperature) are August and September (89.2°F).
The month with the lowest average high temperature is January (83.2°F).

  • Average low temperature in August: 78.2°F

The month with the highest average low temperature is August (78.2°F).
Coldest months (with the lowest average low temperature) are January and February (72°F).

Average humidity in August - San Juan, PR
  • Average humidity in August: 76.4%

The month with the highest relative humidity is October (76.9%).
The month with the lowest relative humidity is March (71%).

Average rainfall in August - San Juan, PR
  • Average rainfall in August: 7.7"

The wettest month (with the highest rainfall) is August (7.7").
The driest month (with the lowest rainfall) is March (3.1").

Average rainfall days in August - San Juan, PR
  • Average rainfall days in August: 18.5 days

Months with the highest number of rainy days are November and December (19.6 days).
The month with the lowest number of rainy days is March (12.2 days).

Average sea temperature in August - San Juan, PR
  • Average sea temperature in August: 84.4°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 August / Average sunshine in August - San Juan, PR
  • Average daylight in August: 12.7h

The month with the longest days is June (Average daylight: 13.2h).
The month with shortest days is December (Average daylight: 11h).

  • Average sunshine in August: 8.6h

Months with most sunshine are March and July (Average sunshine: 9.1h).
The month with least sunshine is November (Average sunshine: 6.7h).

Average UV index in August - San Juan, PR
  • Average UV index in August: 12

Months with the highest UV index are March, April, May, June, July, August and September (UV index 12).
Months with the lowest UV index are January and December (UV index 8).