Some mean minimums and maximum temperatures from last January + difference from normal on the monthly mean. A warm January last year.
Auckland aero,17.5C- 25.7C, +1.6C
Gisborne, 15.7C-25.C, +1.1C
Wellington aero, 16C-23.4C, +1.9C
Christchurch aero, 12.8C-24C, +1.3C
Christchurch Gardens 13.8C-24.7C, +1.8C.
Dunedin aero 9.8C-22.6C, +0.9C
Invercargill aero, 10.1C-19.5C, +0.6C