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São Luís, the capital of Maranhão state, sits on an island on the northern coast of Brazil, where the northeast meets the Amazon region, at approximately 2.53°S, 44.30°W. Close to the equator, it has a tropical climate (Köppen Aw) — hot and humid year-round, cooled by sea breezes — with a very sharp division between a intensely wet first half of the year and a dry second half.
There is no summer in the temperate sense: temperatures stay warm and steady, with daytime highs around 30–31°C all year and warm, humid nights, tempered by ocean breezes. The wet season, from January to June, is when almost all the year's rain falls, in frequent heavy downpours and thunderstorms with high humidity and abundant cloud; March and April are the wettest months.
Nor is there a true winter, but the dry season from July to December is warm, sunny and much less humid, with little rain — some months nearly rainless — and bright, breezy conditions. This drier, sunnier stretch is comfortably the best time to visit, and coincides with the season when the spectacular dune-and-lagoon landscapes of the nearby Lençóis Maranhenses are at their most striking.
São Luís is very wet, receiving on the order of 1,900–2,100 mm of rain a year, overwhelmingly concentrated in the wet season from January to June, with a strong peak in March and April, while the second half of the year is markedly dry. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.
São Luís sits at the transition between Brazil's semi-arid northeast and the humid Amazon, giving it a sharply seasonal climate: a drenching wet first half of the year followed by a dry, sunny second half. The heavy wet-season rains feed the rivers that, as they recede in the dry season, fill the famous lagoons among the dunes of the nearby Lençóis Maranhenses.
To follow any single measurement in Sao Luis more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.