September weather forecast
Guayanilla, PR

September in Guayanilla, Puerto Rico brings slightly cooler temperatures and a hint of rainfall. The high temperature takes a slight dip down to 86.2°F (30.1°C), and the city experiences its year's highest average rainfall of 3.58" (91mm). The touch of a breeze, mixed with rain, lends a gently refreshing feel to the city after months of continuous heat. This gradual transition to cooler climes instills a sense of tranquility in the atmosphere, setting an inviting stage for tranquil evening walks along the city's picturesque waterfront.

Temperature

Guayanilla ushers in September with an average high-temperature of a still tropical 86.2°F (30.1°C), showing a close resemblance to the previous month. The average temperature in Guayanilla drops to a warm 76.5°F (24.7°C) during the night in the month of September.

Heat index

September's average heat index is computed to be a fiery hot 98.6°F (37°C). Undertake additional safety actions, risk of heat cramps and heat exhaustion is significant. Persistent activity may induce heatstroke.
Regarding the heat index, one should be aware it's determined by shaded settings and mild winds. Direct sunlight has the potential to heighten heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', melds the effects of warmth and moisture to generate a feeling of heat. An individual's temperature experience can be influenced by extra factors, including metabolic differences, activity levels, and clothing. Taking into account that direct sunlight can boost the heat effect, the heat index may rise by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are primarily vital for children. Children commonly overlook the importance of rest and fluid replenishment. Thirst, being a delayed sign of dehydration, emphasizes the need to keep hydration up, especially during lengthy physical activities.
Sweat evaporation, driven by perspiration, is the method the human body uses to rid itself of excessive warmth. When the air contains significant moisture, the efficiency of the evaporation process decreases, preventing the body from cooling down effectively and creating a feeling of overheating. When body temperature rises due to excess heat gain beyond its removal capability, one might experience heat-related disorders.

Humidity

In Guayanilla, the average relative humidity in September is 78%.

Rainfall

The month with the most rainfall in Guayanilla is September, when the rain falls for 20.9 days and typically aggregates up to 3.58" (91mm) of precipitation.

Snowfall

September is the only month when snow falls in Guayanilla. The month with the most snowfall days is September, when snow falls for 0.1 days.

Daylight

The average length of the day in September is 12h and 14min.
On the first day of September, sunrise is at 6:12 am and sunset at 6:40 pm. On the last day of the month, sunrise is at 6:17 am and sunset at 6:16 pm AST.

Sunshine

In Guayanilla, the average sunshine in September is 9.4h.

UV index

April through October, with an average maximum UV index of 7, are months with the highest UV index in Guayanilla. A UV Index of 6 to 7 symbolizes a high health hazard from unsafe exposure to UV radiation for the average person.
Note: The UV index of 7 during September translates into the following guidance:
Elude overexposure. Fair-skinned people could get burnt in less than 20 minutes. Limit your direct sun exposure, especially between 10 a.m. and 4 p.m., when UV radiation is strongest. Shade structures might not provide complete sun protection. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays. Take to heart! Snow reflection can almost magnify the Sun's UV radiation twofold.