Last week of May or last week for August for Alps hiking?

It depends on where you go. Some sites/hiking spots may still be closed or dangerous in late May. End of August (4th week) is better. Many tourists, esp. Americans, will be gone.

We were in Mürren mid-May in 2019, and there was still some snow on the ground. The tails above Mürren were still covered with snow. I agree that late August would be better for hiking, at least in that area.

We were in Lucerne, Lausanne, Berner Oberland , Lugano, and Bern in late May - early June in 2019. Temperatures were great, but in the Berner Oberland some (not all) trails were still closed due to snow. The funicular from Murren up to Allmendhubel was not open yet in May, but opened in June.

If hiking is important to you, August is probably better than mid-May. We’d love to return to Switzerland. We decided next time we’d go in August or early September.

Definitely August. We were in Murren late July and it didn’t feel crowded at all. And it was cold at night.

Early September 2019, we had to go up to Birg before we saw snow on the ground. So all of the popular trails from Murren to Lauterbrunnen to Grindelwald were snow free and open. Beautiful time of the year. I'd say late August is your best bet.

Just left Wallis, Unterbaech and am in Bern, Schoenried Gstaad. The smaller lifts did not start running until 19 June. May is probably too early. Not seeing much if any snow at 2000m now. Have stayed near Lucerne 10+ years ago in August and got the most rain in 10 years then. You can't really predict the weather you will get those weeks, but I would opt for August.

Thank you everyone! August/September it is.

What about early July? We are planning a trip for 2022, focusing on the Berner Oberland. The first half of July works best for our schedule but we could delay if this is too early for Alps hiking.

I remember hiking in the Berner Oberland on the 4th of July. That year there was some snow in patches across the highest trails, such as Bachalpsee, Schynige Platte, and a few small patches (crossable) near Mannlichen. Other trails were ok, though a little wetter.

Fall (September) is a much better bet for clear dry weather in Switzerland. There are also fewer tourists.

Weather can be highly variable in May. There may have been heavy rains, even flooding, and streams may not be passable, and hiking trails may be in need of restoration after the long winter. And if it was an especially late spring, places may not even be open at some of the higher elevations.