September weather forecast
Fortaleza, Brazil

September is marked by the dry season in Fortaleza, with the average rainfall amount scarcely changing at 23mm (0.91"). The decrease in rainfall pairs well with steady temperatures hovering near the 30-degree mark. Relative humidity slightly drops as does the temperature of the sea, marking 26.6°C (79.9°F) at its surface. Sunshine hours remain constant at 9.4, ensuring ample daylight to experience the city. Bask in the brilliance of clear skies as September rolls into Fortaleza.

Temperature

The commencement of September introduces an average high-temperature of a hot 30.2°C (86.4°F), closely mirroring the preceding month. Fortaleza experiences a nighttime temperature average of 23.4°C (74.1°F) during September.

Heat index

For most parts of September, the heat index is estimated at a fiery hot 37°C (98.6°F). More protective measures are required - heat exhaustion and heat cramps are likely. Heatstroke may follow lengthy activity.
It is crucial to understand that heat index figures are for shade and gentle wind conditions. Exposing to direct sunshine may enhance heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', is a measure of how hot it feels when the actual air humidity is factored in. This effect is personal, shaped by the individual's physical activity and heat sensitivity, influenced by factors including wind, clothing, and metabolic variances. Direct sun rays have a notable impact on perceived temperature, which can raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly relevant to babies and toddlers. Juveniles are regularly less conscious of the need to recuperate and rehydrate. Thirst is a tardy symptom of dehydration - hydration, especially during lengthy physical activities, should be maintained.
Perspiring is a crucial mechanism for the human body, allowing it to release excessive warmth through evaporating sweat. Increased relative humidity slows down evaporation, thereby decreasing the rate of heat removal from the body, culminating in a sensation of overheating. Overheating and potential dehydration arise when body heat gain eclipses its release capability.

Humidity

The average relative humidity in September is 74.4%.

Rainfall

In Fortaleza, during September, the rain falls for 5 days and regularly aggregates up to 23mm (0.91") of precipitation. In Fortaleza, Brazil, during the entire year, the rain falls for 135 days and collects up to 1608mm (63.31") of precipitation.

Sea temperature

September is the month with the coldest seawater in Fortaleza, Brazil, with an average sea temperature of 26.6°C (79.9°F).
Note: For any water activity, surface water temperatures between 25°C (77°F) and 29°C (84.2°F) are considered as excellent and extremely pleasant for lengthened periods.

Daylight

In September, the average length of the day in Fortaleza is 12h and 5min.
On the first day of September, sunrise is at 05:32 and sunset at 17:35. On the last day of the month, sunrise is at 05:19 and sunset at 17:28 -03.

Sunshine

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

UV index

The months with the highest UV index are January through April, September through December, with an average maximum UV index of 12. A UV Index value of 11, and more, symbolizes an extreme threat to health from exposure to the Sun's UV rays for average individuals.
Note: The daily high UV index of 12 in September translates into this advice:
Take all required precautions, as unprotected skin and eyes can burn in 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. On days when the sun blazes, arm yourself with sunglasses that block UVA and UVB radiation. A sunscreen boasting a minimum SPF of 30 should be generously applied and reapplied even on cloudy days, post swim or outdoor exercise. Heads up! The reflection of sand and water notably intensifies UV rays from the Sun.