windy year round. December is near summer and on a clear (and preferably windless) day it is one of the loveliest places on earth - drive to the top of one of the hills (eg Mt Victoria) and look down at the harbour
http://www.buynz.net.nz/images/web_ready_Wgtn_ harbour_2.jpg
Te Papa museum is fascinating. Sit on a beach, about 5 minutes' walk from the downtown area; stroll round downtown - quite buzzy and much more compact than say Auckland - go out into the east harbour suburbs - I believe Peter Jackson's film studio is out there somewhere. Go up the cable car. For easy daytrips try up the west coast or east over the hills to Martinborough and wine country.