My recently updated estimate of how monthly average daily maximum temperatures have varied in NZ from 1863 to 2021:
https://diymetanalysis.wordpress.com/20 ... land-tmax/
There is pretty good agreement with the NIWA 7-stations, which only goes back to around 1910 . The Berkeley Earth (BEST) reconstruction fails badly before around 1940, which I believe is due to the fact that NIWA supplies only a paltry number of stations to GHCN