Originally Posted by indyfabz

Mid to third week of June. Slight chance of iffy weather, but you'll avoid the worst of the crowds and, although it's been getting warmer earlier there (it was 70- in Missoula the other day), you're more likely to have snow on peaks then and far less likely to have to deal with forest fires and their smoke. All but one of my recent trips out of Missoula have started around June 15th. I am home before the 4th of July.

Some popular national parks out west, including Glacier, are expecting such large crowds this year that you have to make a reservation to even get into them. Hikers and bikers are excluded from the reservation requirement.