When to Go
Although the Southern Alps and Fiordland have four distinct seasons, it's not unusual for the mountains to get snow even in summer. If you're traveling in winter, check the weather forecasts and road conditions regularly. The road into Milford Sound can close for days at a time because of snow or avalanche risk and you must carry chains.
For winter sports, from July through September you can be assured of snow around Queenstown and Wanaka, where the ski scene is ushered in by the Queenstown Winter Festival. In the height of summer—from January to March—both resort towns have a lot of Kiwi holidaymakers. If you're planning on hiking one of the major trails, such as the Milford Track, summer or early autumn are the best times, but you'll need to book well ahead.