From 17th street, terminal #2 isn't very far a walk and there are even sidewalks to walk on all the way. Entering the port from any other direction when walking isn't an option. I often leave the ship to go shopping when moored at Term #2 or 4 when doing a B2B and have no problems re-entering with my cruise card so I can only imagine that showing a boarding pass would also be sufficient.
This time of year the weather is very nice for a mid morning walk & it's not hot at all.