New Zealand's climate history is being rewritten following the chance discovery of some extremely rare diaries from the middle of the 19th century.
An English missionary documented thousands of meticulous weather observations - 177 years ago.
Richard Davis, based in Waimate North in the Bay of Islands, started his first weather diary in 1839 but the pages lay for decades in Auckland Library before being stumbled on by a climate researcher.
Niwa's Andrew Lorrey says he quickly realised it was of national significance to our science.
The earliest known long term weather records in New Zealand span nine years, with Mr Davis recording temperatures twice daily at 9am and noon and also atmospheric pressure at noon.
That was a bit of a mindbender.- Niwa scientist Andrew Lorrey
And they contain a few surprises, including two consecutive days with snow on the hills in 1849.
The research team believes the reverend was usually spot on after cross referencing his numbers against records from passing ships.
The data now forms the basis of a research paper titled The Dirty Weather Diaries which is a phrase used throughout the diaries.
The paper is part of a global project and Niwa climate scientist Petra Pearce says the observations will go into an international climate database that's trying to recreate climate at six hourly intervals across Earth.
And Ms Pearce says Niwa has given mr Davis the title of NZ's first meteorologist because of the length and detailed nature of the data he took.