E7, if I were to pick one month it would be July. June has spring snowmelt runoff concerns and the hot August weather can put the river tempts too high on fish that have had a lot of summer pressure on them. The exceptions for August are for some of the glacially fed larger rivers such as the mentioned Kootenai. And the 3 forks of the Flathead river system near GNP (Glacier National Park). They will usually have a good cutt bite still going in August. The Yellowstone and Madison get some cold spring water that can keep them up and cool thru August also. But July is tough to beat for overall good fishing conditions. Usually wink .

RT