September weather forecast
Manaus, Brazil

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Cloudy skies above the Amazon Theatre building in Manaus, Brazil
Cloudy skies above the Amazon Theatre building in Manaus, Brazil

Weather in September

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.
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Frequently asked questions

What is the warmest month in Manaus?

The average temperatures in Manaus, Brazil, reach their apex in September, averaging 32.9°C (91.2°F) at the high end and 23.5°C (74.3°F) at the low end.

How hot does it get in Manaus in September?

In Manaus, 32.9°C (91.2°F) is the average high-temperature and 23.5°C (74.3°F) is the average low-temperature during September. The average heat index (a.k.a. 'felt air temperature', 'real feel'), which takes the relative humidity and factors it into the air temperature reading, in September is calculated to be 46°C (114.8°F).

What is the least humid month in Manaus?

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

What is the average humidity in September in Manaus?

In September, the average relative humidity is 77%.

How much does it rain in Manaus in September?

In Manaus, Brazil, in September, during 6 rainfall days, 74mm (2.91") of precipitation is typically accumulated.

How many hours of daylight does Manaus have in September?

In September, the average day length in Manaus, Brazil, is 12h and 5min.

What time are sunrise and sunset in September in Manaus?

In September, on the first day of the month, sunrise is at 05:58 and sunset at 18:01. On the last day of the month, in Manaus, sunrise is at 05:45 and sunset at 17:53 -04.

How long on average sun shines in September in Manaus?

The average sunshine duration in September is 6.7h.

What are the months with the highest UV index in Manaus?

The months with the highest UV index in Manaus, Brazil, are January through May, August through December, with an average maximum UV index of 12.

How high is the UV index in September in Manaus?

In Manaus, the average daily maximum UV index in September is 12. A UV Index value of 11, and more, symbolizes an excessive health risk from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average UV index

Average temperature in September
Manaus, Brazil

Average temperature in September - Manaus, Brazil
  • Average high temperature in September: 32.9°C

The warmest month (with the highest average high temperature) is September (32.9°C).
The month with the lowest average high temperature is February (30.4°C).

  • Average low temperature in September: 23.5°C

The months with the highest average low temperature are October and November (23.7°C).
The coldest month (with the lowest average low temperature) is July (22.7°C).

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Average humidity in September
Manaus, Brazil

Average humidity in September - Manaus, Brazil
  • Average humidity in September: 77%

The month with the highest relative humidity is March (88%).
The months with the lowest relative humidity are August and September (77%).

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Average rainfall in September
Manaus, Brazil

Average rainfall in September - Manaus, Brazil
  • Average rainfall in September: 73.7mm

The wettest month (with the highest rainfall) is March (335.4mm).
The driest month (with the least rainfall) is August (47.3mm).

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Average rainfall days in September
Manaus, Brazil

Average rainfall days in September - Manaus, Brazil
  • Average rainfall days in September: 6 days

The month with the highest number of rainy days is March (20 days).
The months with the least rainy days are August and September (6 days).

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Average daylight in September /
Average sunshine in September
Manaus, Brazil

Average daylight in September / Average sunshine in September - Manaus, Brazil
  • Average daylight in September: 12h and 1min

The month with the longest days is December (Average daylight: 12h and 18min).
The month with the shortest days is June (Average daylight: 11h and 54min).

  • Average sunshine in September: 6h and 4min

The month with the most sunshine is August (Average sunshine: 7h and 18min).
The month with the least sunshine is February (Average sunshine: 3h and 6min).

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Average UV index in September
Manaus, Brazil

Average UV index in September - Manaus, Brazil
  • Average UV index in September: 12

The months with the highest UV index are January, February, March, April, May, August, September, October, November and December (UV index 12).
The month with the lowest UV index is July (UV index 10).

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Manaus, Brazil

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