Santa Catarina

Santa Catarina sits on Brazil's southern Atlantic coast between Paraná to the north and Rio Grande do Sul to the south, with Florianópolis on the long Ilha de Santa Catarina its capital and Joinville and Itajaí on the mainland its main commercial ports. The tide signature here is small and mixed — mean range at Florianópolis is about 0.5 metres, semidiurnal in pattern with two highs and two lows of unequal size, climbing past 0.8 metres on the largest spring tides and dropping close to flat on neaps. The astronomical forcing is small because the South Atlantic at this latitude is broad and the continental shelf relatively narrow, so the tide propagates as a near-progressive wave rather than amplifying through resonance. What matters more on a day-to-day basis is wind setup from the south-quadrant frentes that sweep up from the Roaring Forties and stack water against the coast — sustained 25-knot south winds can lift apparent water level 30 to 50 cm above predicted, and the same wind builds the surf on the open Atlantic-facing beaches. Florianópolis sits at the centre of one of the country's strongest surf cultures; the breaks at Joaquina, Praia Mole, and Praia da Galheta on the open eastern coast read the swell more than the tide, while the protected western coast on the bay side at Sambaqui and Santo Antônio de Lisboa hosts the local oyster-farming industry where tide does set the working hours. Marinha do Brasil's Centro de Hidrografia da Marinha (CHM) runs the authoritative gauge network and tide tables. Open-Meteo Marine drives the gridded predictions on this site.