SeasonMapAlter do Chão weather in December
Brazil
December in Alter do Chão: hot, soaked, with muggy air — fine if you can take 23 rainy days.
#7 of 12 months in Alter do Chão · #803 of 1383 destinations to visit in December · comfort 66/100 (tier C)
Updated September 2026 · climate normals from ERA5 reanalysis
Traveller notes on Alter do Chão in December
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Alter do Chão climate normals — December
| Daytime high | 30°C / 85°F | 🥵 hot |
|---|---|---|
| Nighttime low | 27°C / 80°F | |
| Rainfall | 315 mm / 12.4 in | ⛈ soaked |
| Rainy days | 23 days | |
| Humidity | 75% | 💦 very humid |
| Dew point | 24°C / 74°F | |
| Sunshine | 9.5 h/day | |
| Daylight | 12.3 h | |
| Wind | 14 km/h / 9 mph | |
| Air quality (US AQI) | 52 | 🙂 moderate |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Alter do Chão in December
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Peak crowdsRiver beaches emerge, Summer holidays in Brazil, school holidays in 3 of the markets that fill it(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Alter do Chão's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherAlter do Chão's weather peaks July–September.
Best weatherFair weatherToughest weather
What's on in Alter do Chão in December
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Season
River beaches emerge
1 Aug – 31 Jan · usuallyHigh waterCrowdedThe Tapajós drops from August and the white sandbanks in front of the village come back out of the water. By September you can wade to the Ilha do Amor, and in a hard year walk to it.
- Season
Wet season
MonsoonRisk23 rainy days and about 315 mm in the month — the real kind of rainy season, not afternoon showers.
from the climate normals
Where is Alter do Chão?
Alter do Chão in December — FAQ
- Is December a good time to visit Alter do Chão?
- December in Alter do Chão: hot, soaked, with muggy air — fine if you can take 23 rainy days. It ranks #7 of 12 months for Alter do Chão on SeasonMap's comfort score (66/100).
- What is the weather like in Alter do Chão in December?
- In December, Alter do Chão averages a daily high of 29.6°C and a low of 26.6°C, with about 315.1 mm of rain over roughly 23.2 rainy days.
- What is the air quality in Alter do Chão in December?
- Alter do Chão has a mean US Air Quality Index of about 52 in December.