September weather forecast
Vieques, PR

As September sets in, Vieques begins to see a gradual decline in both temperature and rainfall. The climate remains quite cosy with its slightly cooler mornings and enchanting sunsets. Despite the decrease in rainfall and wind intensity, this month marks the high cloudiness season with 33% cloud cover, adding an extra layer of beauty to the island sky. Tropical storms are likely but infrequent with plenty of good weather days. September allows visitors to enjoy a less crowded and more peaceful atmosphere on the island.

Temperature

September's advent denotes a minor fluctuation in the average high-temperature to a still warm 84°F (28.9°C) from August's 84.2°F (29°C). Vieques sees a minor drop to an average minimum temperature of 80.8°F (27.1°C) during the night in the month of September.

Heat index

September's heat index is appraised at a hot 93.2°F (34°C). Ensure additional precautions, heat exhaustion and heat cramps may be expected. Heatstroke could occur from sustained activity.
Heat index evaluations are typically in the context of light winds and shaded environments. Under direct sunshine, the heat index values might be elevated by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'feels like', binds temperature metrics with humidity values to give a sense of the actual warmth. A person's impression of weather can be shaped by several aspects, among them metabolic variations, pregnancy, and levels of physical activity. It is essential to realize that direct sunlight can escalate the perceived temperature, increasing the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Kids are usually more vulnerable than adults, given their lesser sweating ability. Along with their larger skin surface relative to their small stature and the excess heat due to their activity, their risk is amplified.

Humidity

The average relative humidity in September is 78%.

Rainfall

In Vieques, in September, it is raining for 19.6 days, with typically 1.77" (45mm) of accumulated precipitation. In Vieques, Puerto Rico, during the entire year, the rain falls for 216 days and collects up to 21.5" (546mm) of precipitation.

Ocean temperature

With an average ocean temperature of 84.9°F (29.4°C), September is the month with the warmest seawater.
Note: Swimming, diving, and other water activities in temperatures ranging from 77°F (25°C) to 84.2°F (29°C) are highly enjoyable and provide prolonged comfort without unease.

Daylight

In Vieques, the average length of the day in September is 12h and 14min.
On the first day of the month, sunrise is at 6:07 am and sunset at 6:35 pm. On the last day of September, sunrise is at 6:11 am and sunset at 6:10 pm AST.

Sunshine

In September, the average sunshine in Vieques is 9.1h.

UV index

The months with the highest UV index are January, March through December, with an average maximum UV index of 7. A UV Index value of 6 to 7 symbolizes a high health risk from unprotected exposure to Sun's UV rays for the ordinary person.
Note: In September, a daily maximum UV index of 7 leads to the following instructions:
Beware of overexposure. Fair-skinned individuals risk burning in less than 20 minutes. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Be attentive! The UV exposure is heightened with reflections from sand and water.