Have you considered Merimbula NSW?
Maybe not as close to the snow but not that far either - 2.5hrs to Thredbo.
One of the best wavesailing spots in NSW - great wind in summer - longer season and warmer than NZ. Flatwater sailing also available 15K north just before Tathra.

Hey mate, I have just moved over from Christchurch to WA. The windsurfing is good in the summer. You get a good seabreeze that comes in, but it can die off. Many times I have left work at 4pm to find that it is dead at 4.30, plus you have to match the wind and tide. Generally most people go to the estuary on a easterly seabreeze. It is shallow (shoulder height) and flat flat water.
The Nor-west comes in gusty and strong. There is a good place at sumner beach that is great for wavesailing on the nor-west. It is off shore, so you have to be careful.
Contact the guys at Groundswell at the estuary, they are really keen and a great bunch of people. Go to www.kitesurf.co.nz
As far as other sports go.. it is all at your fingertips. Snowboarding only lasts untill the start of October thought.

The nor-easter is mostly on shore.The waves aren't that large, but good for hitting with heaps of speed. Most of the wave sailing is on the nor-west. I have used a slalom and jp85. You will nead at least a short wetsuit in summer. Not too sure about up north near Amberly. I have only sailed on the estuary, sumer and lake ellesmere. Lake clearwater at the foot hills of the alps is apparently really good. The port hills in chch are great for mountainbiking. You can mountainbike in the morning then drive 10min and go for a windy.
But Taranaki in the north island is the wave sailing capital of NZ. They are having the wave classic on labour weekend.