Bernina Express in Sept

I took the Bernina Express route once in late September as a basic mode of transport from Lake Como to Switzerland. I enjoyed it a lot, despite a gray day. However, I don't think I would detour from your other planned destinations. An extra day in the Berner Oberland gives you an extra shot at the best weather and views there, without the extra travel time and money. The BO and Provence can each keep you busy for quite a while.

I'm not sure that there is a best time. I've ridden it in summer and spring, and seen videos of winter.

I would have thought that the deciduous leaves should be making a nice show and the trip would be a fine one.

2 days?

For me the Bernina Express is a fantastic trip, no matter what time of the year you do it! And yes I have done it in just about every month of the year. In late September you are most likely to see it much as in summer, with the exception that the days are shorter and less warm, on the other hand if autumn comes early you may be lucky enough to experience some of the wonderful autumn colours. Either way it will not disappoint.

Best time? Dead of winter on a brilliant clear day.

Good data, all. Thanks

We rode the Bernina Express at the very end of September last year. We spent two nights in Samedan on the way and had a full sunny day for a lovely hike. The following day we boarded the train in cloudy weather and it stayed that day for the ride over thepassof and down to Tirano, but the views were still wonderful. The larches were just starting to turn to gold; the lake near the summit was steely grey, and as we rode down the other side I got some great photos of puffy clouds in the valley far below us.

I will add that we were on a regional train, not the "real" Bernina Express. This was an advantage as we had a car practically to ourselves---there were 6 people total, and all of us enjoyed moving back and forth across the aisle to see the best views.