September weather forecast
Upala, Costa Rica

Weather in September in Upala, Costa Rica, marks the transition from the wet months of the summer to the drier autumn months. A significant decrease in rainfall promptly changes the city's weather characteristics. Also, while the overall temperature and humidity remain stable, the average number of sunshine hours increases slightly. Daylight hours fall slightly to 12.2 hours, marking the gradual departure of the long summer days.

Temperature

September's beginning signals an average high-temperature of a still moderately hot 29.8°C (85.6°F), barely different from August's 29.6°C (85.3°F). During the month of September, the temperature falls to an average of 23.8°C (74.8°F).

Heat index

September's heat index is appraised at a sweltering 38°C (100.4°F). Undertake special precautions, the probability of heat exhaustion and heat cramps is high. Prolonged activity may provoke heatstroke.
Always consider that heat index estimations are for light winds and places in the shade. The heat index values could be amplified by up to 15 Fahrenheit (8 Celsius) degrees in direct sunlight.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', is an aggregate value of air's warmth and moisture to show the human-felt temperature. The individual's impression of temperature can be affected by numerous factors such as metabolic variations, physical exertion, and attire. Given the impact of direct sunlight, it's noteworthy that the felt temperature can rise by 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Kids generally face higher risks than adults as they sweat less. Along with their large skin surface compared to their small bodies and higher heat production due to their activities, their vulnerability is increased.
One way the human body deals with excessive warmth is by perspiring and allowing sweat to evaporate. Under conditions of high relative humidity, the rate of evaporation decreases. This results in the body retaining more heat than under conditions of dry air. Rising body temperatures due to excess heat retention could signify impending heat disorders.

Humidity

In September, the average relative humidity in Upala is 83%.

Rainfall

In Upala, during September, the rain falls for 28.6 days and regularly aggregates up to 176mm (6.93") of precipitation. Throughout the year, in Upala, there are 295.8 rainfall days, and 1656mm (65.2") of precipitation is accumulated.

Daylight

In September, the average length of the day in Upala is 12h and 11min.
On the first day of the month, sunrise is at 05:30 and sunset at 17:49. On the last day of September, sunrise is at 05:28 and sunset at 17:30 CST.

Sunshine

The average sunshine in September is 8.1h.

UV index

March through June, August and September, with an average maximum UV index of 7, are months with the highest UV index in Upala. A UV Index estimate of 6 to 7 represents a high health risk from exposure to the Sun's UV radiation for ordinary individuals.
Note: The UV index of 7 during September translates into the following guidance:
Stick with precautions and abide by sun safety procedures. Evading sunburn is essential. Avoid direct exposure to the Sun between 10 a.m. and 4 p.m., the peak period for UV radiation, noting that objects like parasols or canopies might not offer complete sun protection. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key.