... to some extent on the thread you are using. I use 210 Danville Flymaster Plus for my thread leaders. It is a synthetic that does not absorb water. Perhaps other threads do absorb water and would perform differently when used in furled leaders.

I've fished in below freezing temps a good number of times with the Danville leaders, both fishing dry flies and nymphing. As most around here know, I prefer my furled leaders to submerge, and that is true regardless of weather conditions. I can't recall one of my leaders ever freezing, even partially, while it is being fished.

First, most of the water picked up by the leader, said water being quite a bit above the freezing point, will be cast off on the first back cast, or at least on the following false cast.

Second, the leaders are so supple that the casting action will keep them largely free of ice even if there were some minor freezing going on. As soon as the leader is back in the water ( submerged ) any minor accumulation of ice on the leader would melt off in the above freezing temps of the water.

I have had had leaders get a bit stiff while moving from point to point. The leader still shakes out supple and is ready to go as soon as you shake out some line.

John

P.S. One BB member mentioned when this subject came up a couple years ago that she had an issue with thread furled leaders sticking to ice formation around the water during really cold weather. I believe she changed to furled mono leaders for those conditions. I haven't had that kind of problem with the thread leaders I use.

P.S.1 Are you aware of the Saturday morning fly tying demonstrations at Jimmy's All Season Angler in Idaho Falls, from 10:00 a.m. to 1:00 p.m. ?? I surely do miss those sessions. Consistently the best fly tyers in the region and always a bunch of great guys and gals attending. If you go, give my regards to Jimmy.