I thought it might be of interest to cite the names of some reference materials from the pre-online days. Various public and university libraries probably have at least some of them - the ones I searched in past years were mainly Wellington Public library and Victoria University. It is possible that MetService and/or NIWA may have complete collections of the ones directly produced by them and their predecessor organisations.
"Statistics of New Zealand", 1853-1927, carried reports giving monthly and annual commentary and summary stats. for NZ's climate stations - a dozen or so of them were listed with an increase in the number of stations in the later years. From 1928-1987, a much more detailed version appeared in
"NZ Met. Misc. pub. 109 (Meteorological Observations)". An abbreviated set of annual stats. and brief commentary also appeared for many years in the
New Zealand Yearbook - I'm not sure of the starting and ending dates (it may be that a short report still appears ...). Annual summaries at this level of detail ceased (with a couple of exception years) until about 2000, when NIWA online reports were produced.
For month by month reports and statistics,
The New Zealand Gazette (reports easily located in its index entry under "Meteorological ...) carried detailed reports and statistics for the years
1868-1987 inclusive {there are some older "provincial gazettes" with regional reports in them, as well}.
In addition, daily readings and a brief summary commentary for the "Government Observatory" (various Wellington sites, Kelburn from 1928) appeared until early 1943
(**). The reports appeared as separate appendices to the main gazette content over most of the period.
The reports included a detailed "weather sequence" for that month, though from 1985 this was replaced by daily MSL analysis maps. For many years, the Gazette extract/supplement was known as "NZ Met. Misc. pub. 107".
After 1987, the same or similar printed content was still available from MetService and later NIWA in various forms until December 2008. Weather sequence commentary in a much more abbreviated form reappeared, and anomaly charts were added.
What I acquired: Apart from devouring all this stuff over a period of years in libraries, I subscribed to a copy of the Gazette extract from January 1955. It was interesting to get some clues as to matters of social and economic concern from these commentaries, and watch the style of language change over the years. The price in 1955 was 5/- per year, increasing to about $240 in 2008.
(**): The "dailies" for Kelburn stopped just before I was born, which frustrated me somewhat when I discovered that. They later became available from CliFlo, though sunshine daily data is only listed from 1954.