If you're looking for summer vibes, the best time to travel to Great Falls, MT is in August, July and June, when the average temperature reaches 23.61 °C, while July, August and June are the 3 sunniest months of the year, with an average of 155.54 hours.
If you prefer colder temperatures, however, make sure you visit Great Falls, MT during the months of January, December and February to experience an average of -9.15 °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 Great Falls, MT is 4.73 mm, while the months of January, February and March are drier, with an average of 0 mm.