Hi Mark -
<<"Good point. Since I have never been in Wengen in mid to late June, I don’t have any first hand knowledge but i’ve seen that others report June can be iffy.">>
In June 2015, my grandson graduated from high school and we had a window of a few days in his schedule, in which he could join me during a previously planned trip to Switzerland. We stayed on the Rigi, at Sugiez, at Ligerz, and two nights at the Schönegg in Wengen, before driving back to Zürich via Luzern for dinner with friends on the night of the 16th before he flew back to the USA on the morning of June 17th. Lunch on the quai at the Rathauskeller by the Limmat on the 16th was sunny and nice.
The Männlichen to Kleine Scheidegg trail opened on the 14th or 15th for the full distance, but it was open a week or two before that, as far as the stretch around Tschuggen that doesn't get much sun.
Another year, well before that visit, at the other end, the snow on the trail a few meters from the KS station was 2 meters deep on June 6th.
We went up to Männlichen on the 15th, and started the walk. My knee was troublesome, and the promised few hours sunny interval in the cloud cover barely materialized for a few minutes of partial clearing.
So, after a few hundred meters of only partial visibility, we gave up. Went back down and over to Mürren, which was completely socked in except for a few moments now and then, had a 5 minute break in the fog/clouds to look at part of the Mönch and Jungfrau, had lunch, went to Brienz and walked around below the cloud deck. We picked up a music box at Jobin for his cousin, returned to Wengen, had a wonderful meal at the Schönegg, and left the next AM, as the day was clearing up and the sun was starting to breakthrough. I recall that it was a nice day after we left.....as my Swiss friends always say....."too bad you could not have stayed another day. It was really beautiful just after you left!"
We heard that often enough on Spring trips that we moved our Alpine visits to September, where - on average - we and I have had much better luck, as attached - second image.
The moral of the story is - try to get at least a couple of days for an alpine stay, especially in June. And, the weather is changeable and unpredictable in the high Alps, sometimes even a few hours in advance.
For example, as we came up to Wengen on the 14th, from below a cloud deck, we had the classic view along the valley open up for about an hour, and saw a view from the station as we got off the train, quite similar to the third attached image from the Hotel Eiger. It was, though, not quite as clear. Good for about an hour, then , gone.
Up at Männlichen there was lots of dreary looking piles of snow along the trail, with patches of clear ground in the meadows where the sun could reach.
It looked something like the first picture ( attached from late May in 2005). Except, there was still a lot more snow around, and you could not see very far. Certainly, could not see the Eiger. The sky was not visible except for a few moments now and then. Memory is unreliable, but I recall not being able to walk the trail in May 2005, because it was closed at Tschggen, so I had to content myself with that kind of photo.
Others have reported nice weather recently in Wengen in May.
Rule of thumb- the trails at and above 2000 meters open about June 15th. +/- one week or 10 days. No promises for cloudless skies. But, they happen. And, if the snow pack from the previous Winter is light, it can be sooner.
There are webcams:
en.swisswebcams.ch/suc he/ort/m%C3%A4nnlichen -6935774/