Jun 6, 2018 - 12:14 AM
You could expect climbers on the mountain at any time during summer, although, counterintuitively, it can be more dangerous during periods of warm weather because of the danger of rock fall.
As far as seeing climbers on the mountain, you would need a telescope to see anything, and you would need a good idea of the route they were taking. The face is massive and climbers would be difficult to spot. You won't see much from Grindelwald because not much of the north face is visible from there. Kleine Scheidegg would be a bit better, but i think the best view would be somewhere directly opposite the mountain where the entire face is visible. If you take the gondola to Maennlichen and walk back following the gondola cables you will find great views of the mountain, but you will need binoculars or a spotting scope to see any climbers. If you look at a map, somewhere like Alpiglenn would seem ideal, but it is actually too close and even though the Eiger towers over you there, all you can really see is the foot of it.