In September, the weather in Montemor-o-Novo is typically warm. Average daily high temperature in September is about 27 degrees above zero. On average, Montemor-o-Novo has 26 sunny, 2 rainy, and 2 partly cloudy days in September. The rains are usually light. September as well as May, June, and October is considered the most comfortable time to visit Montemor-o-Novo.