September · Brazil
Best time to visit Alter do Chão in September Weather, crowds & prices
Weather in Alter do Chão in September
Average temperature 32°C, 18 mm of rain, about 28 days with 6+ hours of sunshine and 60% humidity — based on the five most recent complete years of ERA5 data (2021–2025).
September score
9.9/10
Ranked #1 of 12 months
- Avg temp
- 32°C
- Rainfall
- 18 mm
- Humidity
- 60%
- Days with 6h+ sun
- 28
- Crowd Density
- Moderate Crowds
- Average Expenses
- $$$ · Peak Season Rates ($$$)
September in Alter do Chão scores 9.9/10 for beach and coastal travel - the single best month of the year. Expect around 32°C, 18 mm of rain, and roughly 28 days with 6+ hours of sunshine this month.
The 'Caribbean of the Amazon'—white-sand river islands and clear Tapajós water—peaks in the low-water months from August through December.
September in Alter do Chão — the year's strongest window
September averages 32°C (89°F), so the practical pattern is early mornings, a long midday break, and evenings back outside.
Expect 18 mm of rain — occasional showers rather than washed-out days — alongside about 28 days with 6+ hours of sunshine and 12 daylight hours.
On our climate-comfort scale this is the top-ranked month of the year for Alter do Chão at 9.9/10 — the reference point every other month on this page is measured against.
Pack the lightest breathable clothing you own, a hat, and more water than feels necessary.
Plan for peak pricing, with crowds are moderate. You are paying the year's highest rates for the year's best conditions — book early or shift a few weeks either side.
Frequently asked
- What is the weather like in Alter do Chão in September?
- In September, Alter do Chão averages 32°C, 18 mm of rain, and about 28 days with 6+ hours of sunshine. Its climate-comfort score is 9.9/10.
- Is September a good time to visit Alter do Chão?
- September earns a 9.9/10 climate-comfort score. Use the year-round chart to weigh the weather against your budget and crowd preferences.
- How much does it rain in Alter do Chão in September?
- Expect about 18 mm of rain in September. Average humidity is 60% and there are about 28 days with 6+ hours of sunshine.
Curated in Alter do Chão
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Things to do in Alter do Chão
Alter do Chão, Brazil. Live activities and tours from GetYourGuide, matched to this destination.