Waikato and Bay of Plenty rainfall are already at record levels, and extreme rainfall levels are being recorded across the north and east of the North Island, and along the eastern South Island.
"January to September rainfall records have been smashed in the Waikato and greater Bay of Plenty region," meteorologist Georgina Griffiths said.
"It has also been an extremely wet year-to-date for Auckland."
Auckland and Tauranga have had their fourth wettest year in observations since 1962 and 1898, respectively.
Many locations, including Tauranga, Te Puke, Hamilton, Gisborne, Rotorua, Taupo, Paraparaumu, Christchurch and Ashburton have all received more rain so far in the nine months of 2017 than they usually get in the year.
"For many of us, 2017 may well be remembered as the year it didn't stop raining," Griffiths said.
The year-to-date rainfall accumulation at Hamilton Airport (1271mm) was the highest January-September tally since records began in 1935.
It was also the wettest period at Ruakura (1234mm, records since 1905), Rotorua (1717mm, records began in 1963), and Taupo (1091mm, records since 1976).
It was the second wettest January - September period for Te Puke (2020mm, records since 1958), and the third wettest January -September period at Pukekohe (1271mm, records since 1986).
The wet weather is forecast to continue next week after a settled and warm weekend, with the western and northern regions getting the worst of it.
"Lows continue to target New Zealand. It is almost like we've got a bullseye on our back," Griffiths said.
MetService is asking farmers and growers to keep in touch with its rural forecasters on social media.
