This is a fun thread. I just happened upon it today.
I think you can assume the workshop in North Carolina is similar to Atlanta if it is attended by similar people. Industry and profession matter much more than location. I have never found I need to dress differently to work conferences in different part of the country. Now if you want to leave the hotel to sight see, than by all means research the weather and dress appropriately for the weather. I still remember how cold I was one year in San Francisco for a June conference.
Internationally this may be a little different. Most European countries and Asian countries don't have AC as arctic as we do. I found I need different clothes when I go to Asia, for example.
Other have also said, being overdressed in a professional setting is somewhat easier than being under-dressed. At most, I can get away with blue jeans but they are probably never the best thing to bring to conferences. Depending how casual your capris are, they may be in this category too.
Anyway, good luck on your next conference. I think if you just put on your favorite outfit for work, you are probably okay.