I was in the Lauterbrunnen, Murren, Gimmelwald area during mid to late September, and all of the trains and lifts were running then. You will have some closures starting in October.
The hotels and restaurants were open and weren’t too crowded. I had made reservations, but was able to extend my stay for an extra night in my last hotel to take advantage of a beautiful day so I could hike some more.
The weather was good with some rainy and cloudy days, but that’s a possibility any time of the year. There were some beautiful warm sunny days and several cloudy days that were still good for hiking. It was a little chilly at times, but I never used the thick layer I brought just in case it got cold. I did wear a sweater some nights while walking around town.
Most of the cows had been taken down to lower pastures, but there were still some up in the mountains.
I visited Gimmelwald on two separate days; there were other tourists, but not crowded. The cable cars were running to both Stechelberg and to Murren.
All the best,