The city of São Luís experiences a very marginal dry-summer tropical savanna climate (Köppen climate classification: As), bordering on a tropical monsoon climate (Köppen climate classification: Am). The city possesses a short dry season from August to November. During this period when the equatorial rainband associated with the highly seasonalized positioning of the Intertropical Convergence Zone is not over the city, warm to hot temperatures and abundant equatorial sunshine prevail. Conversely, the humid, rainy wet season dominates the remaining majority of the year, with abundant cloud cover prevalent and heavy rains falling from December to July, with the heaviest rainfall and highest cloud cover from January to May. The cloudiest month of the year is March with a monthly average of 107.2 hours of bright sunshine throughout the month, while the sunniest month of the year is August with a monthly average of 260.3 hours of sunshine throughout the month. The wettest month is April with an average monthly total of of rain, while the driest month is October with an average total rainfall of . On average, nearly 70 per cent of annual rainfall is recorded from February to May.