September weather forecast
Manaus, Brazil

September is a transitional period as the city starts to experience the onset of the wet season. Temperature highs rise further to 32.9°C (91.2°F) but offer a decent amount of sunshine hours. Rainfall begins to increase compared to the summer months however the high temperatures and clear periods make the weather bearable. Parrot watching becomes particularly rewarding around this time as many species begin their nesting period.

Temperature

The month of September sees the highest average temperatures, reaching 32.9°C (91.2°F) at the peak and 23.5°C (74.3°F) at the low.

Heat index

September's heat index is calculated to be a blazing hot 46°C (114.8°F). Be wary: Heat exhaustion and heat cramps are highly anticipated. With continued activity, heatstroke is very likely.
It is emphasized that the heat index's values are meant for shaded zones with mild winds. A rise in the heat index by 15 Fahrenheit (8 Celsius) degrees may result from direct sunlight exposure.
Note: The heat index, also known as 'feels like' or 'apparent temperature', stands as a testimony to how temperature and humidity combine to impact our sense of warmth. A person's impression of weather can be shaped by several aspects, among them metabolic variations, pregnancy, and levels of physical activity. Considering the impact of direct sunlight, it's possible for the heat index to surge by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially vital to children. Children often fail to understand the importance of rest and rehydration. Thirst is a late manifestation of dehydration - hence, it is crucial to stay hydrated, especially during ongoing physical activities.
To achieve cooling, the human body employs perspiration, relying on the subsequent evaporation of sweat. An increase in relative humidity disrupts body cooling by slowing the evaporation rate, thereby reducing the rate at which the body cools and amplifying the sense of heat. If heat absorption exceeds the body's cooling ability, body temperature can elevate, resulting in potential thermal illnesses.

Humidity

The months with the lowest humidity in Manaus, Brazil, are August and September, with an average relative humidity of 77%.

Rainfall

In Manaus, during September, the rain falls for 6 days and regularly aggregates up to 74mm (2.91") of precipitation. Throughout the year, there are 160 rainfall days, and 2307mm (90.83") of precipitation is accumulated.

Daylight

The average length of the day in September is 12h and 5min.
On the first day of the month, sunrise is at 05:58 and sunset at 18:01. On the last day of September, sunrise is at 05:45 and sunset at 17:53 -04.

Sunshine

In Manaus, the average sunshine in September is 6.7h.

UV index

The months with the highest UV index are January through May, August 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 unsafe exposure to UV radiation for ordinary individuals.
Note: The UV index of 12 during September translates into the following guidance:
Practice every precaution of necessity, unprotected skin and eyes might burn in minutes. Stay in the shade and limit sun exposure from 10 a.m. to 4 p.m., when UV radiation is most potent. Keep in mind that shade structures like parasols or canopies do not offer full protection. Prioritize a wide-brim hat for comprehensive sun defense for your face, neck, eyes, and ears. Even on cloudy days, a sunscreen with a minimum 30 sun protection factor should be generously applied and frequently re-applied, including after every swim or outdoor exercise.