Visiting local bars in Sao Joao do Marinheiro is more fun in good weather. These rainfall averages and temperatures can help you choose the best time for bar hopping. The hottest months are usually September and October with an average temp of 79°F, while the coldest months are June and July with an average of 71°F. The rainiest months in Sao Joao do Marinheiro are January, December, February, and March, with each month seeing an average of 9 inches of rainfall.