For surface temps there is a part of coast watch they gives the surface temps but as far as rivers I done think so .. There may be individuals on spacifac rivers that give those updates but I don't know who to ask for that info ... I know Wilson's fergus does for the grand in the summer months
The water is very cold right now. Once u see active rolling fish, that will be the right temperature.
some say 52 degrees, I would say that at 42 degrees plus, fish can be caught in numbers
updated water temps for lake Ontario today .... wow temps are really changing... what a hot day today ... should cause lots of fish moment in the water