New Zealand first cause Feb. nearly always gives us th best weather for visiting/touring there...South Islands great, but there are areas like th Coromandel in th North Isl. that is choice also.
"Midlife" is correct that it can get hot here jus north of th Sunshine coast as with everywhere in QLD that time of year, so maybe time your Northern NSW/QLD touring toward th end of your holiday, as you may wing some cooler weather near th end of March...other than that, spend th most of your time in th southern states for more favourable weather.