Re: How cold is too cold?
My experience this winter (I fish in PA) has been that when water temps were in the 37-39 degree area, the best I could hope for was to pick up the odd fish on small pheasant tails fished slow and deep. At the upper end of your range 42 degrees, they got a little more active although it was still a slow presentation. But, at least you didn't seem to have to bounce the nymph off of their head to get them to eat it. I recorded water temps specifically to get an idea about this.These were smaller freestone and limestone streams.