Climate averages 1991–2020
Rio de Janeiro weather
in September.
A warm, moderately wet month: the 8th warmest and the 4th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Rio de Janeiro: daytime highs average 26.8°C and nights cool to about 18.6°C. By daytime temperature it is the 8th warmest of the 12 months.
Expect about 75 mm of rain on roughly 11 days, which makes September a moderately wet month (the 4th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 11 h 57 min on an average September day.
The nearest other city in this atlas is São Gonçalo (16 km away). In September its highs average 26.3°C, 0.6°C cooler than Rio de Janeiro, with 85 mm of rain.
Among the 448 cities listed in Brazil, Rio de Janeiro ranks joint 253rd of 448 for the warmest September highs and joint 264th of 448 for the driest September (rainfall, lowest first). The mean September high of those 448 cities is 27.5°C; Rio de Janeiro is 0.7°C cooler than that mean.
From September to October, average highs rise by 1.1°C to 28.0°C, and monthly rainfall rises from 75 mm to 92 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Rio de Janeiro climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 30.7°C23.5°C | 23.5°C | 170 | 16.4 | 13.413 h |
| February | 31.2°C23.6°C | 23.6°C | 118 | 13.3 | 12.913 h |
| March | 29.6°C23.0°C | 23.0°C | 145 | 16.7 | 12.212 h |
| April | 28.0°C21.4°C | 21.4°C | 88 | 12.0 | 11.612 h |
| May | 25.6°C19.0°C | 19.0°C | 76 | 11.1 | 11.011 h |
| June | 25.2°C17.8°C | 17.8°C | 48 | 7.3 | 10.811 h |
| July | 24.9°C17.1°C | 17.1°C | 51 | 7.9 | 10.911 h |
| August | 25.9°C17.5°C | 17.5°C | 41 | 7.5 | 11.311 h |
| September, selected | 26.8°C18.6°C | 18.6°C | 75 | 10.5 | 11.912 h |
| October | 28.0°C20.0°C | 20.0°C | 92 | 11.7 | 12.613 h |
| November | 28.0°C21.0°C | 21.0°C | 139 | 15.8 | 13.213 h |
| December | 29.7°C22.6°C | 22.6°C | 151 | 16.2 | 13.514 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- São Gonçalo in SeptemberBrazil · 16 kmHigh 26.3°C · Low 18.1°C · 85 mm rain
- Duque de Caxias in SeptemberBrazil · 19 kmHigh 27.1°C · Low 18.2°C · 86 mm rain
- Barra da Tijuca in SeptemberBrazil · 21 kmHigh 27.5°C · Low 19.0°C · 75 mm rain
- Belford Roxo in SeptemberBrazil · 27 kmHigh 27.3°C · Low 18.3°C · 66 mm rain
- Magé in SeptemberBrazil · 32 kmHigh 26.3°C · Low 17.6°C · 85 mm rain
- Nova Iguaçu in SeptemberBrazil · 32 kmHigh 27.4°C · Low 18.1°C · 66 mm rain
- Maricá in SeptemberBrazil · 37 kmHigh 26.0°C · Low 19.2°C · 61 mm rain
- Itaboraí in SeptemberBrazil · 38 kmHigh 25.9°C · Low 17.4°C · 82 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Rio de Janeiro) is explained once on the Rio de Janeiro year overview and on the Sources, method and limits page.
Barra da Tijuca lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.