Ilha Grande weather in August

August in Ilha Grande: nice, a little rain, with muggy air — an excellent time to visit.

Updated September 2026 · climate normals from ERA5 reanalysis

Ilha Grande🇧🇷 Brazil · Southeast Brazil · Island80
  1. 71Jan
  2. 77Feb
  3. 78Mar
  4. 81Apr
  5. 84May
  6. 84Jun
  7. 85Jul
  8. 80Aug
  9. 85Sep
  10. 78Oct
  11. 79Nov
  12. 77Dec

#6 of 12 months in Ilha Grande · #676 of 1413 destinations to visit in August · comfort 80/100 (tier A)

Days
17°C
Nights
13°C
Wet days
10
Sun
8.5 h
Humidity
78%
Daylight
11 h
Ilha Grande, Brazil
Photo: Pedro Slinger · Pexels

Traveller notes on Ilha Grande in August

Regulars are specific this counts as the coolest, driest part of the year here, genuine winter in Rio state though nothing close to actually cold, pleasant temperatures the norm throughout. Our row backs that cool, genuinely wet read, 16.8C over 13C nights feeling 12C, with 76.7mm of rain across 9.7 days and humidity at 78 percent. Regulars are consistent most bars, restaurants and pousadas stay open despite the island being noticeably quieter, prices running lower and weekends specifically more lively than weekdays. Windy conditions can make scuba diving less reliable this month even though most other activities stay unaffected. The sea sits at a mild 22.9C. The record: 8.5 hours of sun, a 14 kph wind and AQI 65.
CoolestDriestPartOfYearNotActuallyCold · August · 1 month ago · Read more on Tripadvisor ↗

Other months in Ilha Grande

Regulars genuinely disagree on this month: one names it great weather, with the heaviest rain confined to December through March and already behind by now, while another calls it a poor choice specifically for a beach-and-forest island because tropical rain is still a real risk. Our row backs the wetter view more than the drier one, a real 145.3mm of rain across 14.5 days, alongside mild-for-Brazil temperatures, 19.3C over 16.4C nights. Regulars broadly agree this and the other shoulder months, April through June and September through November, offer the best balance of decent weather, thinner crowds and lower prices compared with the December-March peak. The sea holds a warm 25.9C regardless of the air. The record: humidity 80 percent, 9.3 hours of sun, a 12.2 kph wind and AQI 62.
OpinionsSplitOnWhetherAprilIsGoodOrRainy · April · 1 month ago · Read more on Tripadvisor ↗
Regulars say May and June are not much of a rainy season on this stretch of coast, with one caveat attached: you can be unlucky and land on a cold front, which brings overcast and drizzle for its duration. One visitor here from late April into May reported the rain confined to a few days and the sunny ones hot but not excessively. Our row is cooler than that suggests - 17.9C days over 14.8C nights, the sea still holding 24.7C from the summer - with 77.6mm across 10.8 days and 9 hours of sun. On crowds, this is the quiet half of the year, mostly travellers rather than holidaymakers, though weekends fill and mid-May is the sweet spot. No cars on the island, so the trails are the point. The record: humidity 79 percent, a 12.1 kph wind and AQI 57.
UnlessAColdFrontArrives · May · 1 month ago · Read more on Tripadvisor ↗
September is the end of the cooler, drier winter run regulars date from June, and a first-week visitor describes good atmosphere without crowds. A caution about our own figures: the 17.8C here reads far cooler than anyone describes the beaches, because the grid square takes in the island's forested high ground rather than the shore - the 24.1C sea is the number to trust for Lopes Mendes and Abraao. What the month does carry is 76mm across 11.2 precipitation days, and the island's best day out depends on it: the four-beach boat trip runs to Praia do Pouso and then a forest trek to Lopes Mendes, and needs decent conditions. Abraao is where you wait one out. The record: humidity 81 percent, 9.5 hours of sun and AQI 76.
TrustTheSeaFigureHere · September · 1 month ago · Read more on Tripadvisor ↗
July is the month locals name for Ilha Grande - Brazilian winter, and the driest and sunniest part of the island's year, with more sun and less cloud than the summer brings. Forum accounts of late July put it at 23 to 27C with cooler nights and water that is not warm. Our own row reads far colder at 16.5C, which belongs to the island's high ground rather than its beaches, since Ilha Grande rises to nearly 1,000m behind Abraao - so take the forum's figure as the one for sea level. The boat day everyone recommends strings Mangues, Pouso, Lopes Mendes and Santo Antonio together, with Lopes Mendes reached by boat and then a short walk through the forest. The record: 6.9 precipitation days carrying 41.7mm, 9 hours of sun and a 22.4C sea.
SeaLevelNotTheRidge · July · 1 month ago · Read more on Tripadvisor ↗

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Ilha Grande climate normals — August

Daytime high17°C / 62°F😎 nice
Nighttime low13°C / 55°F
Feels like (high)17°C / 63°F
Sea temperature23°C / 73°F🙂 pleasant
Rainfall77 mm / 3 in🌦 some rain
Rainy days10 days
Humidity78%💦 very humid
Dew point11°C / 51°F
Sunshine8.5 h/day
Daylight11.3 h
Wind14 km/h / 9 mph
Air quality (US AQI)65🙂 moderate

Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.

Crowds in Ilha Grande in August

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.

Shoulder seasonan ordinary month(estimated)

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Peak crowdsBusyShoulder seasonQuiet

Best months for Ilha Grande'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 weatherIlha Grande's weather doesn't swing hard through the year — comfort stays fairly steady in every month.

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What's on in Ilha Grande in August

Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.

  • Season

    Clear water and empty trails

    1 May – 31 Aug · usuallyDry season

    The storms stop, the sea settles and underwater visibility is at its best of the year; the island is quiet enough that half the pousadas take the month off. Cool for swimming by August.

What's on around the world in August →

Nearby, and something's on

Within 300 km of Ilha Grande — a day trip or a short hop — with something on this month. Never part of the comfort score.

Where is Ilha Grande?

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Ilha Grande in August — FAQ

Is August a good time to visit Ilha Grande?
August in Ilha Grande: nice, a little rain, with muggy air — an excellent time to visit. It ranks #6 of 12 months for Ilha Grande on SeasonMap's comfort score (80/100).
What is the weather like in Ilha Grande in August?
In August, Ilha Grande averages a daily high of 16.8°C and a low of 13°C, with about 76.7 mm of rain over roughly 9.7 rainy days.
What is the air quality in Ilha Grande in August?
Ilha Grande has a mean US Air Quality Index of about 65 in August.

Within 300 km: Rio de Janeiro's Ipe trees in flower around 15 Aug – 30 Sep, and São Paulo's Ipe trees in flower around 1 Jul – 30 Sep.