Question for you Kiwis out there (down there?)

Hey my friends in NZ ... I have been dreaming of visiting for a long time, and life has flung a chance my way. I'll be in Sydney, AU in the third week of October this year. I've been there before, and it will be interesting to see how things have changed since the turn of the century.

I was planning to hop right over to NZ and start exploring, but the more I read the more worried I am about the weather. I want so much to do a little tramping on the south island, and see the caves and volcanos in the north. You have worms that make light! How cool is that! But now I'm worried that November will be too cold to hike. Even if I go north first and take a few weeks to meander south, will it be warm enough for the snow to melt and do some walking in that beautiful high country?

It's overwhelming trying to pick things to see. I know what I recommend in the USA - I avoid the cities and go to the mountains and national parks out west, but everything in NZ looks so dang gorgeous that I don't see how to begin to narrow it down. Any advice?

November will be fine for hiking...I'm sorry it took so long to see this!

Just want to add remember your layers for dressing.
The weather will play to the extremes, perfectly safe enough if you're prepared.
Merino is AMAZING! Try and find it online and it'll cost you an arm and a leg, might be easier to find it from The Warehouse, Kmart or Postie plus when you are here.