Glacier National Park is open every day of the year and visitors can enter the park at anytime. It goes without saying though, that the seasons are vastly different, and weather conditions dictate when visitor facilities open and close.
The most popular season is summer, from around late May to early September, when all facilities are open and most of the park is accessible.
Bike riders and visitors looking for a little more peace and quiet, find springtime in Glacier to be a compelling destination.
Fall is quieter and a great time to see changing foliage, but visitors need to be more self-reliant as facilities begin to close down for the season.