Flooding on Porana Road outside Pak'nSave, Wairau. Photo: RNZ / Nick Monro
Seventeen North Island locations have observed their wettest-ever January on record.
Niwa data shows January brought unprecedented rainfall.
In Northland, Auckland, Waikato and western Bay of Plenty, events with five times more rain than normal were common.
The northern and eastern North Island saw several consecutive storms that each delivered a typical month's worth of rainfall or more.
In contrast, 18 South Island locations observed record lows for rain.
Invercargill observed its driest January since records began in 1900.
Wānaka was New Zealand's driest location, recording just 4mm of rain for the entire month.