If you're looking for summer vibes, the best time to travel to Oshawa is in July, June and August, when the average temperature reaches 20.53 °C, while July, September and August are the 3 sunniest months of the year, with an average of 118.04 hours.
However, if you prefer colder temperatures, make sure you visit Oshawa during February, January or March to experience an average of -3.66 °C.
For those who don't care too much about temperatures, but want to avoid getting wet in the rain, it's important to avoid travelling during February, March and November, when the average precipitation in Oshawa is 9 mm, while the months of January, February and March are drier, with an average of 0 mm.