The station run by Brazil's national meteorology institute, Inmet, at Mirante de Santana in northern São Paulo recorded 75.4 millimeters of rain between 9 a.m. Friday and 9 a.m. Saturday. Inmet said it was the largest 24-hour total measured anywhere in Brazil in that period, and the state Civil Defense confirmed the record. The storm flooded streets across the city and left two men missing in Jandira, in Greater São Paulo.

The downpour pushed September's total at Mirante de Santana, where the city's historical rain series began in 1943, to 198.2 mm in just 12 days. That already ranks as the fourth wettest September on record at the station, behind 1983 with 243.1 mm, 1993 with 206.7 mm and 2015 with 201.7 mm, according to Inmet data compiled by CNN Brasil. With more rain forecast before the end of the month, the ranking could still change. Only January, with 256.4 mm, has been wetter at the station this year, G1 reported.

Floods and missing people in Greater São Paulo

Around 1 a.m. Saturday, two men aged 32 and 33 were swept away by a river current during a flood on Avenida Antônio Bardella, in the Jardim São Luiz neighborhood of Jandira, a city in São Paulo's metropolitan region. According to the police report filed in Jandira, one of the men was in the flooded area when the other and his 32-year-old sister tried to rescue him. The current dragged all three, and the woman only got out of the water after grabbing trees on the riverbank. She received medical care but lost sight of the two men. The Fire Department is searching for them with support from the municipal Civil Defense.

Between midnight and 1:20 p.m. Saturday, the Fire Department logged 48 calls related to rain and wind in the city and its metropolitan region: 20 floods, 16 fallen trees and 12 structural collapses. Lanes of the Marginal Tietê, the expressway that runs along the Tietê river through the city, were blocked by flooding for much of Saturday, and the river ran a risk of bursting its banks, according to Estadão and UOL.

Amazon moisture feeds the storms

Meteorologists at Climatempo, in an account published by CNN Brasil, attribute the record volume to three factors: a cold front around the September 7 holiday left 35.6 mm on September 5 and 6; from September 9, an area of low pressure over Paraguay and southern Brazil pushed a new cold front through on Friday, with instability moving from Paraná state toward São Paulo; and the low-level jet, a stream of warm, moist air flowing from the Amazon, carried humidity toward São Paulo, Paraná and Mato Grosso do Sul and fed the buildup of heavy clouds. In other words, part of the water that flooded Brazil's largest city traveled across the continent from the Amazon rainforest.

State Civil Defense says it is monitoring conditions with radar and satellites and has teams mobilized. It advises residents to avoid flooded areas or fast-moving water, never try to cross inundated roads and seek safe shelter during storms.

"Numbers like these show why monitoring cannot stop. Information and risk awareness are what allow people to protect themselves in this period. Prevention is what saves lives," said Colonel Araújo Monteiro, São Paulo state's civil defense coordinator.

Free SMS alerts are available by texting the postal code of a location to 40199; the emergency numbers are 193 for the Fire Department and 199 for Civil Defense.

The outlook stays poor in the short term. For Sunday, Climatempo expects rain all day and night in the capital, with temperatures between 14°C and 16°C. Unstable weather should last through Monday, ease from Tuesday, and a polar air mass off the Southeast coast is expected to keep temperatures below 20°C until September 17.