The south islands west coast is often renowned for being the wild west, with a lot of bad weather and heaps of rain. However don't let this put you off, as although the west coast does get a bit of rain, it also gets a lot of sunshine is often quite warm, with parts of the west having an almost sub tropical feel. This is also the reason the west coast has its beautiful, thick, lush bush, providing stuning scenery.
The west coast gets plenty of south and west swells coming up from the deep south, providing very consistant surf, its not often that the west coast is flat. The west coast doesn't have the large population of the big east coast cities and therefore doesn't get very crowded in the water either, Its not hard to find good surf to yourself. All the main surf spots are between Greymouth and Karamea, with the other areas to the south and north not quite as accessible.
When you find the surf flat be sure to check out the pancake rocks and blowholes at Punakaiki, best at high tide for the blowholes. See Shanty Town and Try your hand at gold panning. Near Hokitika you can see the glow worms at night. there are several other craft produced from green stone carving to glass blowing. There are many other things to keep you busy, including many walking tracks.