I was down there on the 8th and 10 respectively droppign off and pickign up from the poultry show, definately not t-shirt weather, but I found a sweater lived up to it's name and made me sweat.
Given the clouds moving in temps will have dropped a bit. so pack warm, it's down on the coast, and all that water is a great heatskink, so temps are pretty even, not as cold overnight as here in the hills or in the waikato basin. but it's still chilly.
hmm, I suppose thats a long winded way of saying, "Thermals" just like cantyguy
figure on 10 degree days and -2 nights and you shouldn't be far off. A bit warmer than the 8 degrees and -5 here.