Monthly climate guide
Rio Branco weather in September
Expect very hot weather in Rio Branco in September: afternoons reach about 34°C (94°F), while nights drop to around 23°C (73°F). Around 78 mm of rain falls over the month (some rain), and skies are often cloudy. Daytime highs are 2°C warmer than August and about the same as October.
What stands out in September
- Just 450 km apart, but Rio Branco runs about 2°C cooler than Porto Velho this month.
- Rain is well below Rio Branco's usual level (around 43% less).
- Nights stay warm, rarely below 23°C — air-conditioning helps.
- It's one of the drier stretches of the year in Rio Branco.
September is typically Rio Branco's warmest month.
Avg high
34°C
94°F
Avg low
23°C
73°F
Rainfall
78 mm
some rain
Humidity
69%
relative
Sky
59%
cloud · often cloudy
Rio Branco weather by month
Show the monthly averages as a table
| Month | Avg high | Avg low | Rain | Humidity | Cloud cover |
|---|---|---|---|---|---|
| January | 28°C / 83°F | 23°C / 73°F | 254 mm | 92% | 87% |
| February | 28°C / 83°F | 23°C / 73°F | 241 mm | 93% | 88% |
| March | 28°C / 83°F | 23°C / 73°F | 242 mm | 93% | 85% |
| April | 28°C / 82°F | 23°C / 73°F | 147 mm | 92% | 73% |
| May | 28°C / 82°F | 22°C / 71°F | 80 mm | 91% | 61% |
| June | 28°C / 83°F | 21°C / 70°F | 38 mm | 88% | 45% |
| July | 30°C / 86°F | 20°C / 68°F | 20 mm | 79% | 36% |
| August | 33°C / 91°F | 21°C / 70°F | 44 mm | 69% | 44% |
| September | 34°C / 94°F | 23°C / 73°F | 78 mm | 69% | 59% |
| October | 33°C / 92°F | 24°C / 74°F | 115 mm | 73% | 79% |
| November | 31°C / 88°F | 24°C / 74°F | 189 mm | 81% | 81% |
| December | 29°C / 84°F | 23°C / 74°F | 208 mm | 90% | 83% |
What to pack for September
- Light, breathable clothing (cotton or linen)
- A sun hat and high-SPF sunscreen
- A refillable water bottle
- An extra layer — evenings are noticeably cooler than afternoons
- A compact umbrella or packable rain jacket
- Water-resistant shoes
Is September a good time to visit Rio Branco?
Compare the months in the chart above to find your ideal window.
Best time to visit Rio Branco →Other Brazil cities in September
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Rio Branco weather in September. WeatherCompare, 2026 (NASA POWER / ERA5, 2011–2020 monthly averages). https://weathercompare.eu/weather/brazil/rio-branco/september
<a href="https://weathercompare.eu/weather/brazil/rio-branco/september">Rio Branco weather in September</a> (WeatherCompare)
<iframe src="https://weathercompare.eu/embed/brazil/rio-branco" width="300" height="160" style="border:0;border-radius:12px" loading="lazy" title="Rio Branco weather in September"></iframe> <p style="font-size:12px"><a href="https://weathercompare.eu/weather/brazil/rio-branco/september">Rio Branco weather in September</a> – WeatherCompare</p>
Rio Branco in September: quick answers
Is September a good time to visit Rio Branco?
It can be, if you like heat: September highs in Rio Branco are around 34°C. Good for the beach; plan sightseeing for early morning and evening.
How warm is Rio Branco in September?
Average highs are about 34°C (94°F) and average lows about 23°C (73°F), based on 10 years of daily data.
Does it rain a lot in Rio Branco in September?
Rio Branco typically gets around 78 mm of rain in September — some rain.
Figures are long-term averages for the area around Rio Branco (NASA POWER / ERA5, 2011–2020), not a forecast for a specific year. For upcoming days, see the live multi-source forecast.