Any  advice  on weather  likely  to encounter on this trip?It travels over  a large  area,with  varying  altitudes, so  seems  different kinds of clothing may  be  needed.

Layers are best, it may be cool at the start, but, should get warmer as you go south. Having said that I went in October and the morning at Little Big Horn was warm, but, the weather got worse going towards Yellowstone, and it was cold and rainy in Cody.

Although it snowed overnight, Yellowstone was sunny and warm although the road to Jackson was blocked, we stayed overnight in West Yellowstone and went back into the Park the next day,by the afternoon, the road to Jackson had cleared so we weren’t held up.

Keith

You are in for a treat! Second best JY holiday ever, after Australia. I always considered the Grand Canyon to be spectacular, but other parks and canyons are equally impressive in completely different ways.

You really need to prepare for everything ranging from hot, dry desert conditions to possible snow. Answer is plenty of different layers to suit all conditions.