Rio de Janeiro
Brazil
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Rio de Janeiro, Brazil

September, the first month of the spring, in Rio de Janeiro, is still a warm month, with average temperature fluctuating between 19.4°C (66.9°F) and 25°C (77°F).

Temperature

In Rio de Janeiro, the average high-temperature in September is almost the same as in August - a still moderately hot 25°C (77°F). In Rio de Janeiro, the average low-temperature is 19.4°C (66.9°F).

Humidity

In September, the average relative humidity is 78%.

Rainfall

In September, in Rio de Janeiro, the rain falls for 13.7 days. Throughout September, 47mm (1.85") of precipitation is accumulated. Throughout the year, in Rio de Janeiro, there are 192.5 rainfall days, and 812mm (31.97") of precipitation is accumulated.

Sea temperature

September is the month with the coldest seawater, with an average sea temperature of 21.6°C (70.9°F).
Note: For most, swimming in 21.6°C (70.9°F) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 21°C (69.8°F) to 15°C (59°F).

Daylight

In Rio de Janeiro, the average length of the day is 12h.

Sunshine

In Rio de Janeiro, the average sunshine is 7.9h.

UV index

The month with the lowest UV index is September, with an average maximum UV index of 5. A UV Index estimate of 3 to 5 represents a medium vulnerability from unprotected exposure to the Sun's UV rays for average individuals.
Note: The daily maximum UV index of 5 interpret into the following advice:
Take precautions - Protection against the skin and eye damage is obliged. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.

What is the temperature in September in Rio de Janeiro?

The average high-temperature, in September, in Rio de Janeiro, Brazil, is 25°C (77°F), while the average low-temperature is 19.4°C (66.9°F).

What is the average humidity in September in Rio de Janeiro?

In Rio de Janeiro, Brazil, the average relative humidity in September is 78%.

How many days does it rain in September in Rio de Janeiro?

In Rio de Janeiro, during September, the rain falls for 13.7 days and regularly aggregates up to 47mm (1.85") of precipitation.

What is the month with the coldest sea water in Rio de Janeiro?

With an average sea temperature of 21.6°C (70.9°F), September is the month with the coldest seawater in Rio de Janeiro, Brazil.

What is the sea temperature in September in Rio de Janeiro?

In Rio de Janeiro, the average seawater temperature in September is 21.6°C (70.9°F). For most, swimming in 21.6°C (70.9°F) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 21°C (69.8°F) to 15°C (59°F).

How many hours of daylight does Rio de Janeiro have in September?

The average length of the day in September in Rio de Janeiro, Brazil, is 12h.

How many hours of sunshine does Rio de Janeiro have in September?

In Rio de Janeiro, Brazil, the average sunshine in September is 7.9h.

When is the lowest UV index in Rio de Janeiro?

With an average maximum UV index of 5, September is the month with the lowest UV index in Rio de Janeiro.

What is the UV index intensity in September in Rio de Janeiro?

The average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium health risk from unsafe exposure to the Sun's UV rays.
Average temperature in September - Rio de Janeiro, Brazil
  • Average high temperature in September: 25°C

The warmest month (with the highest average high temperature) is February (29.7°C).
The month with the lowest average high temperature is July (24°C).

  • Average low temperature in September: 19.4°C

The month with the highest average low temperature is January (23.7°C).
The coldest month (with the lowest average low temperature) is August (18.5°C).

Average humidity in September - Rio de Janeiro, Brazil
  • Average humidity in September: 78%

The month with the highest relative humidity is November (82%).
The month with the lowest relative humidity is August (76%).

Average rainfall in September - Rio de Janeiro, Brazil
  • Average rainfall in September: 47mm

The wettest month (with the highest rainfall) is November (119mm).
The driest month (with the least rainfall) is June (29mm).

Average rainfall days in September - Rio de Janeiro, Brazil
  • Average rainfall days in September: 13.7 days

The month with the highest number of rainy days is March (22.7 days).
The month with the least rainy days is July (9.3 days).

Average sea temperature in September - Rio de Janeiro, Brazil
  • Average sea temperature in September: 21.6°C

The best month for swimming (with the highest average sea temperature) is March (25.8°C).
The coldest month (with the lowest average sea temperature) is September (21.6°C).

Average daylight in September / Average sunshine in September - Rio de Janeiro, Brazil
  • Average daylight in September: 12h

The month with the longest days is December (Average daylight: 13.5h).
The month with the shortest days is June (Average daylight: 10.7h).

  • Average sunshine in September: 7.9h

The month with the most sunshine is February (Average sunshine: 8.8h).
The month with the least sunshine is October (Average sunshine: 7.5h).

Average UV index in September - Rio de Janeiro, Brazil
  • Average UV index in September: 5

The month with the highest UV index is January (UV index 7).
The month with the lowest UV index is September (UV index 5).