September in Puerto Viejo de Sarapiquí is the hottest month of the year. In September, the weather in Puerto Viejo de Sarapiquí is typically hot. Average daily high temperature in September is about 28 degrees above zero. On average, Puerto Viejo de Sarapiquí has 29 rainy and 1 partly cloudy day in September. The rains are usually heavy. September as well as January, April, May, and June is considered the most uncomfortable time to visit Puerto Viejo de Sarapiquí.