October in Orillia is the rainiest month of the year. In October, the weather in Orillia is typically warm. Average daily high temperature in October is about 12 degrees above zero. On average, Orillia has 21 rainy, 6 sunny, 2 cloudy, and 2 partly cloudy days in October. The rains are usually heavy. October as well as March, April, and November is considered the most uncomfortable time to visit Orillia.