will be late summer going into Autumn and we are having a fairly good summer so HOPEFULLY it'll be lovely and warm. the nights can be colder than you'd think though
NZ weather can be insanely local and you can easily get 4 seasons in one day. Wellington is pretty windy whenever.
the sun is bloody hot and you can get burnt v.easily even when it's overcast. so - hats at all times, lots of sunscreen, a jumper/hoodie/similar whatever for the evenings and rain macs with normal light clothing for the days should cover it.