My husband and I are able to travel somewhat off season and would love to miss the crowds for our Banff/Jasper trip which i am just beginning to plan. I know that July/August is prime time, but if we were to choose between early June or September, which time would be best in terms of scenery and wildlife? I've read many earlier posts and both times seem to be good, but nobody mentioned wildlife. Would be see more traveling spring vs. fall? Also is there a rainy season?

September. Even into early October. We've been several times in late September and even over Canadian Thanksgiving, and that's our favorite time.

Late September. Golden aspen, snow sprinkle, no bugs, fewer tourists, Elks in rut, Bighorns knocking each other, Moose coming out.

Do NOT come in June, as this is usually the rainy season. For years our daughter told us this, so we would come in September. Now that we live here, we find that she was right on about the June weather. In September it is usually nice, but mountain weather can change in five minutes. Bring clothing to layer and a hat and gloves, just in case. Enjoy!

mid september...june, if we have a bad winter...some lakes could still be thawing. wildlife...you can never judge.

September. No guarantees that this will be repeated but this week - September 2013 - nothing but sun and temperatures near 30C.

Wow---this is unanimous---my question has been well answered---thank you so much for your responses---now i'll have to figure out how to split up the time----fly into calgary--drive to jasper and experience the beautiful icefield pkwy. --stay 3 - 4 nights---then drive back slowly, staying near lake louise area and visiting banff---

viewgirl - yup! Good base plan, just a matter of working out the details. Looking forward to hearing from you as you work that out.

Yes, I always rely on fellow fodorites to plan my trips--and have always received great advice and ideas.

Be aware, its the mountains, and anything can happen with the weather. I remember the time we pitched our tent in 14" of snow at Waterton Lakes. That was September 7.
Mind you, it warmed up and the snow was gone, in a couple of days. We definitely had variety, that trip.
And the campground was a popular spot for lots a big-racked mule deer, and BIG bighorn sheep, driven lower by the snow. They were everywhere!
Viewgirl, I like your plan - probably have done the same one a dozen times, usually for 2 weeks, though.
As for wildlife, everyone knows that you have to be out early and late, but you have to research a bit to find the "best" spots for the different species of wildlife. And, you just have to be in the right spot at the right time. This works best, if you are out there a lot.
Often, it seems that there are more elk and deer right in the Banff townsite, than anwhere else. Figures!

September ! best time of the year - But the weather is always unpredictable its always a chance.

Any time is a good time. September is consider shoulder season while June is considered peak. In high mountain Park, snow is possible any time, even June July and August although they are quite rare.