September in Santiago de Querétaro is the cloudiest month of the year. In September, the weather in Santiago de Querétaro is typically warm. Average daily high temperature in September is about 20 degrees above zero. On average, Santiago de Querétaro has 19 rainy, 9 cloudy, and 2 sunny days in September. The rains are usually heavy. September as well as July and August is considered the most uncomfortable time to visit Santiago de Querétaro.