Today is the Autumnal Equinox. In Montana, that means we have almost equal parts day and night (there are exactly 12 hours of each day and night on the equator, but Montana's northerly location means that we have slightly more than 12 hours of daylight.
In terms of our weather, things won't change too terribly much from yesterday. Temperatures will be in the high 60s and low 70s this afternoon, but throughout the week, temperatures will drop slightly each day. Thursday, a cold front will arrive, and it will really start to feel like fall. Rainy, gloomy, and cloudy weather will end the week as another strong low-pressure system moves through the western United States.