I have spent some time in Tasmania and infact just returned from 5 days in Hobart back to my home in Sydney last night.
The weather is going to be a hard call to predict.Melbourne can get 4 seasons in one day.Hobart in February which is exposed to the water and cool winds coming down from Mt Wellington may be cool.
Sydney will be hot, however cloud and southerly breezes can make it very pleasant.
I advise for N.Z. to dress for light cool weather.
Remember we live in the southern hemisphere.Down under.
Maybe living in conditions that prevail from Southern California to Northern California maybe is what you may encounter.
Hope this helps