I-90 between Spokane and Billings When can expect snow?

must tell you I am 70 years old and I remember way back in my high school days a teacher told us he took a group of kids to camp in the area you are talking about and he said it snowed on them the first morning they were there. He was saying it was in July and he and the guys never thought for one minute it would snow up there in July. just goes to show you, it can snow any day of the year up there. It's amazing how I can remember that teacher and I can not tell you what I had for breakfast this morning