For me, one of the few disappointments of Fiesch is the rarity of a relaxing evening waft around in mellow conditions to contrast with the more demanding experiences earlier in the day. Because of the south-easterly orientation of the usual takeoff slope, thermic activity there fades in the afternoon, so lift late in the day must be found elsewhere. There are south-westerly takeoffs above Bellwald, but access is either by car or via a long two-stage chairlift, and this slope never seems very popular. The other side of the valley, which basks in the evening sun, has no uphill transport, but locals say that the trick is to fly over earlier in the day to the Breithorn, top land before it has started working on that side, chill out there until it comes on, and re-launch later!
I have had some success in the late afternoon simply flying directly to Bellwald from Heimat to connect with some rather weird lift there, probably a mix of convergence and thermals. From that, I have got high enough to commit to the main Rhône valley, where several times I have found a large area of gentle convergence right out in the middle. Whenever I have been able to reach the far side with plenty of height, it has then usually been easy to potter around in typical smooth evening thermals, aided by the westerly valley breeze, and return to Fiesch rather than landing out.