August weather forecast
San Juan, PR

Share
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 August

August transitions San Juan into a slightly cooler month while still maintaining notable summer characteristics. The month records the highest sea temperature of the year at 84.4°F (29.1°C), inviting an array of beach activities. Rainfall measures at 1.06" (27mm), providing intermittent respite from the sun-bathed cityscape. The wind speed slightly reduces, and so do the sunlight hours. Together, these conditions constitute a subtly tempered yet still radiant summer month.

Temperature

August, marked by an average high-temperature of 85.1°F (29.5°C) and a low-temperature of 79.2°F (26.2°C), is the warmest month.

Heat index

The heat index value for August is computed to be a torrid 96.8°F (36°C). Preventive measures are required to mitigate the risk of heat cramps and heat exhaustion. Continuous activity may precipitate heatstroke.
In the scope of the heat index, its values resonate with shade and light wind conditions. Exposure to the direct sun might augment heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', is what the temperature feels like to the human body when the air temperature is combined with the relative humidity. Additional elements encompassing metabolic differences, the degree of physical activity, and attire can impact the individual's perception of temperature. Direct sun exposure is noteworthy in its ability to escalate the felt temperature, potentially adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values remain especially vital for babies and toddlers. Young individuals are typically more threatened than adults due to their reduced perspiration. Also, the larger skin surface proportionate to their small bodies and the increased heat from their activities magnify their risk.
The process of perspiration is vital for the human body to get rid of excess warmth by allowing sweat to evaporate. When the level of relative humidity is elevated, evaporation diminishes, causing more warmth to be retained in the body than in dry air. As the body accumulates more heat than it can release, body temperature goes up, increasing the risk of heat-related health issues.

Humidity

In San Juan, the average relative humidity in August is 78%.

Rainfall

In August, the rain falls for 14.8 days. Throughout August, 1.06" (27mm) of precipitation is accumulated. Throughout the year, in San Juan, there are 159.9 rainfall days, and 12.01" (305mm) of precipitation is accumulated.

Ocean temperature

In San Juan, the average seawater temperature in August is 84.6°F (29.2°C).
Note: Water temperature between 77°F (25°C) and 84.2°F (29°C) is perceived as agreeably warm, making all water activities enjoyable without the risk of discomfort over lengthy durations.

Daylight

The average length of the day in August is 12h and 44min.
On the first day of the month, sunrise is at 6:02 am and sunset at 6:59 pm. On the last day of August, in San Juan, sunrise is at 6:09 am and sunset at 6:39 pm AST.

Sunshine

The average sunshine in August in San Juan is 9.1h.

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 risk from unprotected exposure to Sun's UV rays for the average person.
Note: The maximum UV index of 7 during August translates into these guidelines:
Escape overexposure. People with light skin may incur burns in fewer than 20 minutes. The time between 10 a.m. and 4 p.m. is when UV radiation is at its peak. Limit exposure to direct sunlight during these hours. Protect your eyes, ears, face, and neck from the Sun by wearing a wide-brimmed hat. Alert! Sand and water increase UV exposure due to their reflective properties.
Updated: Jul 18, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What month is the hottest?

August is the warmest month, with an average high-temperature of 85.1°F (29.5°C) and an average low-temperature of 79.2°F (26.2°C).

How hot is it in August?

The high-temperature, in August, in San Juan, records 85.1°F (29.5°C), while the low-temperature is 79.2°F (26.2°C). In August, the average heat index (a.k.a. 'apparent temperature', 'feels like'), which calculates the temperature value influenced by the moisture in the air, is computed to be 96.8°F (36°C).

What is the average humidity in August?

In San Juan, Puerto Rico, the average relative humidity in August is 78%.

How many days does it rain in August?

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

How warm is the water in August?

In August, the average ocean temperature is 84.6°F (29.2°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.

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

In San Juan, the average day length in August is 12h and 44min.

What time are sunrise and sunset in August?

On the first day of August in San Juan, sunrise is at 6:02 am and sunset at 6:59 pm. On the last day of the month, sunrise is at 6:09 am and sunset at 6:39 pm AST.

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

In San Juan, the average sunshine duration in August is 9.1h.

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

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

What is the UV index reading in August?

The average daily maximum UV index in August is 7. A UV Index reading of 6 to 7 represents a high health vulnerability from unprotected exposure to UV radiation.

Average temperature in August
San Juan, PR

Average temperature in August - San Juan, PR
  • Average high temperature in August: 85.1°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 August: 79.2°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 August
San Juan, PR

Average pressure in August - San Juan, PR
  • Average pressure in August: 29.97"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 August
San Juan, PR

Average wind speed in August - San Juan, PR
  • Average wind speed in August: 10.3mph

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 August
San Juan, PR

Average humidity in August - San Juan, PR
  • Average humidity in August: 78%

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 August
San Juan, PR

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

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

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 / Average sunshine in August - San Juan, PR
  • Average daylight in August: 12h and 4min

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 August: 9h and 1min

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 August
San Juan, PR

Average sunshine days in August - San Juan, PR
  • Average sunshine days in August: 10.2 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 August
San Juan, PR

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

Average cloud cover in August - San Juan, PR
  • Average cloud cover in August: 32

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 August
San Juan, PR

Average visibility in August - San Juan, PR
  • Average visibility in August: 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

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location