Average Sunshine in Montana for September

Number of Sunny Days

In the table below, the average number of Sunny Days for a city in Montana is the total days this month when the sky is mostly clear. This includes the days when cloud covers up to 30% of the sky during daylight hours.

Partly Sunny Days have cloud covering from 40% to 70% of the sky during the daytime. The rest of the days during September are mainly overcast, with at least 80% cloud cover.

Total Days With Sun is a sum of the Sunny plus Partly Sunny days. All the numbers are averages, made from years of weather watching, for total days in the month.

Amount of Sun

Here's another way to look at how much sunshine a city gets. The % Sun number measures the percentage of time between sunrise and sunset that sunshine reaches the ground. Again, these amounts are monthly averages based on many years of weather observations.