Capt. Marcos Palumbo of the Sao Paulo Fire Department told reporters that mudslides destroyed several houses, killing nine people in the city of Francisco Morato and four in Maripora where another eight people are reported missing.
Two people drowned when they were swept away in floodwaters, one in Guarulhos and the other in Cajamar.
The heavy rains that began Thursday night shut down Sao Paulo's International airport for six hours. Images aired by television stations showed cars covered by water in Francisco Morato and Maripora as well as in parts of Sao Paulo.