The earliest salmon I've ever caught from shore was July 13th one year at Port Credit. That was at the mouth of the river, before they started running up-stream.
I believe that it comes down to water temps, and rain definitely triggers them to enter the rivers.
From my years fishing the mouth of the Credit, I can confidently say that there will be a few early salmon starting to creep into the mouth of the Credit at night right about now... within casting range. Once the sun comes up, they take off into deeper water. So if you are getting the salmon bug, I would try Port credit with glow Cleos from 3 AM to 7 AM.
Here's a map for reference:
[attachment=0]portcredit.JPG[/attachment]
A: This is where most people fish early in the salmon run - Open year round to fishing.
B: This is the end of the boardwalk. From what I remember, a municipal bylaw prevents you from fishing after August 15th (?) But the fishing is good... get the spot right at the end of the boardwalk for best results. The laws may have changed in the last few years since I've been down there so double check.
C: This is an area we call "the Ridgetown".
Fish here at your own risk. Depending on your risk tolerance, the risk can be worth the reward.
Salmon tend to stack up in this area for some strange reason. It's almost as though the marina acts as one giant minnow trap for salmon.
D:
Fish here at your own risk. You're technically not supposed to go around the fence at the end of the boardwalk.