In the Lençóis Maranhenses, the season is not a detail of the trip — it IS the trip. The same place that in July shows off thousands of blue pools between dunes can be, in December, a dry and scorching desert (beautiful, but not what you saw on Instagram). This month-by-month calendar prevents the most common disappointment in Brazilian tourism. The general guide to the park is here.
How the lagoons are born (and die)
The lagoons are accumulated rain: from January to May, the Maranhão winter dumps water that stays trapped between the dunes on top of an impermeable layer. With no rivers to feed them, they spend the rest of the year evaporating under the equatorial sun — about 1 cm a day. The result: a perfect annual fill-and-dry cycle that decides everything.
Month by month
| Months | Situation | Verdict |
|---|---|---|
| January – April | Rain filling the lagoons; tours can be interrupted | Avoid (unless you love rain and solitude) |
| May | Lagoons filling, green sprouting on the dunes, few tourists | An excellent bet in the second half of the month |
| June – August | Lagoons FULL, blue skies, peak season | The high point — June has fewer people than July |
| September | Still full (especially Santo Amaro and Atins), better prices | The clever traveler’s secret |
| October | Dropping fast; the big lagoons still deliver | Acceptable with calibrated expectations |
| November – December | Almost dry; strong heat | Only if the desert itself is the point |
Where the water lasts longest
Not every corner of the park dries at the same rate: the Santo Amaro lagoons are the deepest and hold water into October; those on the Atins circuit and the Lagoa Bonita also resist well; the shallow lagoons of the Lagoa Azul circuit out of Barreirinhas are the first to go. Traveling in September or October, choose your base by the water — the full comparison is in Barreirinhas, Atins or Santo Amaro.
Tips from people who got the season right
- Tours leave around 9am and 2pm — the afternoon one ends with sunset on the dunes: non-negotiable.
- July is absolute high season: book the guesthouse and the 4×4 one to two months ahead.
- The water on the dunes is fresh and warm — the “sleeping fish” (which bury themselves through the dry season) are the most improbable biology lesson in Brazil; watch them, do not fish them.
- Want the lagoons ALL to yourself? The trek on foot reaches where the 4x4s do not go.
🥾 Who is it for?
Effort: light — picking the right month is the whole secret (the lagoons depend on the rain). Children: from May to September, full warm lagoons make it the best season for families. Older travelers and people with reduced mobility: in the lagoon high season the standard tours are enough — no long crossings needed to see the spectacle.
