September weather forecast
Arroyo, PR

Weather in September

September, the first month of the autumn in Arroyo, is also a moderately hot month, with an average temperature varying between 76.3°F (24.6°C) and 85.1°F (29.5°C).

Temperature

In Arroyo, Puerto Rico, the average high-temperature in September is relatively the same as in August - a still warm 85.1°F (29.5°C). In September, in Arroyo, the average low-temperature is 76.3°F (24.6°C).

Heat index

In September, the average heat index is evaluated at a sweltering 97.2°F (36.2°C). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With 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 what the temperature feels like to the human body when the air temperature is combined with the relative humidity. Additional factors like activity, metabolic differences, pregnancy, and clothing affect individual temperature impact. 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. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.
Perspiration is the human body's physiological response to high temperatures and is an attempt to lower body temperature through evaporation of sweat. High relative humidity reduces the evaporation rate, resulting in a lower heat removal rate from the body, causing the perception of being overheated. When heat gain surpasses the level the body can shed, body temperature begins to increase, and consequently, overheating and dehydration can occur, with varying severity.

Humidity

In September, the average relative humidity is 80%.

Rainfall

The month with the most rainfall in Arroyo is September, when the rain falls for 23.7 days and typically aggregates up to 4.29" (109mm) of precipitation.

Ocean temperature

With an average ocean temperature of 85.5°F (29.7°C), September is the month with the warmest seawater in Arroyo.
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 September, the average length of the day is 12h and 14min.
On the first day of the month, sunrise is at 6:09 am and sunset at 6:38 pm. On the last day of September, in Arroyo, sunrise is at 6:14 am and sunset at 6:13 pm AST.

Sunshine

In Arroyo, the average sunshine in September is 9h.

UV index

The months with the highest UV index in Arroyo are May through October, with an average maximum UV index of 7. A UV Index estimate of 6 to 7 represents a high health vulnerability from unprotected exposure to Sun's UV rays for average individuals.
Note: In September, the average maximum UV index of 7 translate into the following recommendations:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. 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 September in Arroyo?

The average high-temperature, in September, is 85.1°F (29.5°C), while the average low-temperature is 76.3°F (24.6°C). In September, the average heat index (a.k.a. 'felt air temperature', 'feels like'), which calculates the temperature value influenced by the moisture in the air, is evaluated at 97.2°F (36.2°C).

What is the average humidity in September in Arroyo?

In September, the average relative humidity in Arroyo is 80%.

What is the rainiest month in Arroyo?

September is the month with the most rainfall in Arroyo. Rain falls for 23.7 days and accumulates 4.29" (109mm) of precipitation.

How many days does it rain in September in Arroyo?

In Arroyo, Puerto Rico, during September, the rain falls for 23.7 days and regularly aggregates up to 4.29" (109mm) of precipitation.

When is the ocean warmest in Arroyo?

The month with the warmest seawater is September, with an average ocean temperature of 85.5°F (29.7°C).

How warm is the water in September in Arroyo?

In September, the average ocean temperature is 85.5°F (29.7°C). For any water activity, surface water temperatures between 77°F (25°C) and 84.2°F (29°C) are considered as excellent and extremely pleasant for lengthened periods.

How many hours of daylight does Arroyo have in September?

In September, the average day length in Arroyo is 12h and 14min.

When is the sunrise / sunset in September in Arroyo?

On the first day of September in Arroyo, sunrise is at 6:09 am and sunset at 6:38 pm. On the last day of the month, sunrise is at 6:14 am and sunset at 6:13 pm AST.

How long on average sun shines in September in Arroyo?

The average sunshine duration in September in Arroyo, Puerto Rico, is 9h.

What are the months with the highest UV index in Arroyo?

May through October, with an average maximum UV index of 7, are months with the highest UV index in Arroyo.

What is the UV index reading in September in Arroyo?

The average daily maximum UV index in September 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 September
Arroyo, PR

Average temperature in September - Arroyo, PR
  • Average high temperature in September: 85.1°F

The warmest month (with the highest average high temperature) is August (85.3°F).
The month with the lowest average high temperature is January (79.9°F).

  • Average low temperature in September: 76.3°F

The months with the highest average low temperature are July and August (76.6°F).
The coldest month (with the lowest average low temperature) is January (71.4°F).

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Average pressure in September
Arroyo, PR

Average pressure in September - Arroyo, PR
  • Average pressure in September: 29.92"Hg

The months with the highest atmospheric pressure are January and February (30.01"Hg).
The month with the lowest atmospheric pressure is October (29.9"Hg).

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Average wind speed in September
Arroyo, PR

Average wind speed in September - Arroyo, PR
  • Average wind speed in September: 6.3mph

The windiest month (with the highest average wind speed) is July (8.6mph).
The calmest month (with the lowest average wind speed) is October (6mph).

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Average humidity in September
Arroyo, PR

Average humidity in September - Arroyo, PR
  • Average humidity in September: 80%

The month with the highest relative humidity is November (82%).
The month with the lowest relative humidity is March (77%).

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Average rainfall in September
Arroyo, PR

Average rainfall in September - Arroyo, PR
  • Average rainfall in September: 4.29"

The wettest month (with the highest rainfall) is September (4.29").
The driest month (with the least rainfall) is February (1.02").

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Average rainfall days in September
Arroyo, PR

Average rainfall days in September - Arroyo, PR
  • Average rainfall days in September: 23.7 days

The months with the highest number of rainy days are May and October (25.3 days).
The month with the least rainy days is February (15.4 days).

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Average sea temperature in September
Arroyo, PR

Average sea temperature in September - Arroyo, PR
  • Average sea temperature in September: 85.4°F

The best month for swimming (with the highest average sea temperature) is September (85.4°F).
The coldest months (with the lowest average sea temperature) are February and March (79.3°F).

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Average daylight in September /
Average sunshine in September
Arroyo, PR

Average daylight in September / Average sunshine in September - Arroyo, PR
  • Average daylight in September: 12h and 14min

The month with the longest days is June (Average daylight: 13h and 11min).
The month with the shortest days is December (Average daylight: 11h and 4min).

  • Average sunshine in September: 9h and 0min

The month with the most sunshine is June (Average sunshine: 10h and 24min).
The month with the least sunshine is December (Average sunshine: 6h and 30min).

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Average sunshine days in September
Arroyo, PR

Average sunshine days in September - Arroyo, PR
  • Average sunshine days in September: 4 days

The month with the most sunshine days is January (8.8 days).
The month with the least sunshine days is May (2.7 days).

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Average UV index in September
Arroyo, PR

Average UV index in September - Arroyo, PR
  • Average UV index in September: 7

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

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Average cloud cover in September
Arroyo, PR

Average cloud cover in September - Arroyo, PR
  • Average cloud cover in September: 32

The months with the most cloud cover are May and July (Cloud cover 40).
The month with the least cloud cover is February (Cloud cover 31).

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Average visibility in September
Arroyo, PR

Average visibility in September - Arroyo, PR
  • Average visibility in September: 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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