I went in February 2012. It only rained once, in the afternoon in Auckland. Having said that, the North Island was having a drought. It was pleasantly warm, but not really shorts weather, jeans and t-shirts with a lightweight jacket for cool mornings, were fine. The South Island was noticeably cooler. I would recommend a hat, scarf and gloves if you intend to go onto the observation platform on the Alpine express. Also, I believe it can be cold and windy at any time on Milford Sound. As always, the best advice is to wear layers. It's an amazing trip, some long days on the road, but worth every minute. One last thing do as many of the flights as you can. Have a fabulous time