Then definately a dress shirt and tie. Jacket would be optional for summertime but if you have a lightweight sport coat, would be most appropriate.
Simple things for interviews to keep in mind...
Remember to turn off your cell phone during the meeting.
No gum or dipping during the interview.
Take along any documents you might have (letters of recommendation, any special licensure etc) and have them in a folder of some sort, not loose in hand.
Be the first to offer your handshake and introduce yourself.
Look them in the eye when speaking. Be confident.
Answer what your asked but don't volunteer lengthy explanations that tend to end up as babble.
We'll keep you in our thoughts and our fingers crossed for you!
Knock 'em dead!