Authorities for di Brazilian state of São Paulo say at least 36 pipo don die for heavy flooding and landslides, wey force some cities to cancel annual Carnival celebrations.
Video show say neighbourhoods under water, full wit motorways and dirty afta houses sweep away.
Rescue teams don dey struggle to reach survivors and unblock roads.
More dan 600mm (23.6 inches) of rain fall for some areas on Sunday, two times di expected amount for di month.
"Search and rescue teams no try to reach some places sake of one chaotic situation," Felipe Augusto, wey be di mayor of di hard-hit town of São Sebastião.
"We never gauge di scale of di damage. We dey try rescue di victims."
Dozens dey miss for di town and about 50 houses don collapse and wash away, Oga Augusto add, e say di situation still dey "extremely critical".
Di state goment bin report at least 35 deaths for São Sebastião and di mayor of Ubatuba, some 80km (50 miles) north-east, say one young girl don die. Hundreds don dey displaced and evacuated.
"Unfortunately, we go get many more deaths," one civil defence official tell newspaper Folha de São Paulo.
Meanwhile, officials say anoda 228 pipo don dey homeless, wit 338 more wey dey evacuated from coastal regions north of São Paulo.
'180-day state of calamity'
One 180-day state of calamity dey declared for six towns for di state: São Sebastião, Caraguatatuba, Ilhabela, Ubatuba, Guarujá and Bertioga.
State Governor Tarcísio de Freitas say im don release di equal of $1.5m (£1.2m) for funding to aid for disaster relief.
Carnival events dey cancelled across di northern coastline, wey be popular destination for wealthy tourists wey dey try avoid huge streetside festivities for di big cities.
Di festival usually last for five days for di run-up to di Christian festival of Lent and di colourful celebrations dey similar wit Brazil.
Latin America largest port for Santos also dey shut as wind speed pass 55km/h (34mph) and wave rise to over one metre, local media report.
President Luiz Inácio Lula da Silva, wey dey spend di carnival weekend for di north-eastern state of Bahia, say e go like visit di affected areas on Monday.
For one post on Twitter, bin send im sorry message to doz wey don lost loved ones and promise to bring authorities togeda to provide healthcare, search for doz wey miss and restore transport and communication infrastructure.
"We go bring togeda all levels of goment and wit di solidarity of society, treat di pipo wey wound, look for di ones wey miss, restore highways, power connections and telecommunications for di region," Oga da Silva write. "My sorry message to di families wey lost loved ones for dis tragedy."
E add say di entire federal goment dey "available and dey work to help wit wetin dey necessary and to join efforts wit di goment of São Paulo and city halls to help di victims".
More heavy rains dey expected for di area, e dey threaten to make conditions even worse for emergency teams.
Extreme weather events like di floods dey expected to become more common as di impacts of climate change take hold.
Last year, heavy rains for di south-eastern city of Petropolis see more dan 230 pipo die.