Banff/Lake Louise in September--good idea?

Yes, it will be chilly. And therefore no mosquitoes. And it is excellent sleeping weather -- bring extra blankets!

We stayed at Johnston Canyon Resort in mid-September a few years ago. We left for Jasper in a light rain, but it changed to snow before Lake Louise. By the time we got to Bow Lake, we were in a whiteout. I used a photo we took of the snow-covered evergreens along the highway, with the Bow Lake and Canadian Rockies in the background on our Christmas card that year.

We kept going despite the snow-packed and slushy road and when we got to Athabaska Glacier, the snow had stopped. Jasper was sunny and light jacket weather.

The moral of my story is: be prepared for any kind of weather and enjoy the beautiful scenery. You won't regret the trip for a minute!

The one place you would have trouble getting to with your rv would be Takakaw falls, a spectacular waterfall located just East of Field, BC up a road with two very tight switchbacks. Our 3/4 ton pick up will barely make it around the corners without backing up. Don't know if your plans included Yoho National park.

This has been very helpful. Thanks to all who replied.

C&J wrote:
Sounds like these Florida residents might find it a bit chilly!

What about driving the parkways inside the national park. Will the roads accommodate a 34 foot RV?

Yes, although parking is a challenge up at Lake Louise. Go very early in the day because the lots get really crowded.

There's also no problem on the wonderful Icefields Parkway heading north from Lake Louise to Jasper, with a very large RV lot at the Icefields Center. The parking lots at the most popular viewing pull-off spots (like Peyto Lake and the waterfalls) can be very full...might be hard to find an RV spot, much less turn around to exit. We barely managed to squeeze in at 25 feet. But we were there in mid-June, so maybe it will be less crowded in September.

Jasper is easier than Banff for RV parking right in town, in my opinion (but we did go early in the day). There are curb sites all along the road by the train tracks across from the lawn of the visitor center. Also across the street on that road by the train tracks is a good grocery store and a couple of fuel stations.

There are no issues with driving your small RV around the Hwys around Banff. When I pull my 5th Wheel I'm over 53ft long and I don't have a problem. My signature says I have a camper which I pick up in September, but as of right now I'm still dragging around a 5th. Wheel.
There are shuttle busses from the Campgrounds in Banff, well there were the last time we were there.
There has been issues with resealable campsites being completely booked because of Canada's 150 birthday and Park entry passes being free ( you still need to pay for campsites and venues) however being late Sept you should be ok.
As for the area bing cold. Heck it can and does snow at any time and in every month h of the year. Which usually in the warmer months only last a day.
Put on a sweater and an extra blanket those temps that were posted earlier are not cold.
Soup.

Sounds like these Florida residents might find it a bit chilly!

What about driving the parkways inside the national park. Will the roads accommodate a 34 foot RV?

C&J wrote:
We are thinking about touring Banff in mid-to-late September in a 34 foot motorhome with no towed-vehicle. Is that a reasonable proposition?

Just be aware that the average temps for the last week of September are
Highs 56-58
Lows 34-35

Fill up on propane you will need it for heat

We don't tow a vehicle either, although we are only 25’, and made it work there in June this year. Parking in the crowded streets of Banff is difficult.

If you can get a copy, the town prints a color brochure called "RV Parking in Banff" which shows some RV lots about 15 minutes (walking) from the town center. Parking on streets is allowed unless the signs say otherwise. Some street parking is marked for RVs "only during summer."

If you stay at the Tunnel Mountain campground, you can do what we did and take the ROAM public transit bus into town and other attractions. It's free leaving the campground, $2 other rides, or $5 for an unlimited adult day pass.

We were there in June of 2015 without a toad. From the Tunnel Mountain campground, there was a free city bus to town. From town, most everything was within walking distance (for us). From the town back to the campground, there was a nominal fee for the bus.

Now, if you want to go much further than town, your RV is the answer. So I think your trip is "reasonable".