It was scorching hot on the Matapedia last week: we saw peak air temperatures of 95 degrees F.--enough to make one believe in global warming.
Early morning water temperatures were in the low sixties. With unusually high air temperatures, salmon fishing for me is a 3:30 a.m. to 10:00 a.m. affair, after which I call it a day. The river has usually not cooled sufficiently to permit evening fishing.
I agree with JR SPEY: catch & release anglers should avoid water temperatures above 65-66 degrees F. Although the salmon of some river systems seem better adapted to warm water (Miramichi), a true conservationist will reel up when the health of the salmon is in any doubt.