A rain gauge in Dunedin city measured 239mm of June rainfall, the most since downtown records began in 2006.
Dunedin airport rainfall records going back to 1962 showed this year's June rainfall of 158mm was beaten only by 168mm of rain in 1972.
And Balaclava rainfall, measured by John Bradley on his own gauge for the National Institute of Water and Atmospheric Research, showed 259.4mm of rain fell this month, the most in any single month since he set up the gauge in 1976.
MetService meteorologist Georgina Griffiths said June was a ''pretty abnormal month'' around the country.
Palmerston North had its wettest June on record, while Wanganui had its third wettest June since records began in 1890, Ms Griffiths said.
There was also ''severe frost nationwide'' last month, with temperatures in part of the South Island getting down to -20degC, she said.
''Minus 20degC days do occur around about four times a century for Central Otago.''
The extreme temperatures and precipitation came together to create a perfect storm of ''horrible'' conditions.
''Every few years ... New Zealand has a horrible winter.''
Most parts of New Zealand would have a drier July than normal, but Otago should expect a July ''normal for rain and for temperature''.
A Niwa seasonal outlook report predicted July-September temperatures would be near average for coastal Canterbury and east Otago, with rainfall ''in the near normal or below normal range''.
Usually, Ms Griffiths said, ''July is the wettest, coldest month of the year''.
