September in San Ignacio is the rainiest and the cloudiest month of the year. In September, the weather in San Ignacio is typically hot. Average daily high temperature in September is about 28 degrees above zero. On average, San Ignacio has 29 rainy and 1 sunny day in September. The rains are usually heavy. September as well as May, June, July, and August is considered the most uncomfortable time to visit San Ignacio.