Auckland is heading for its second wettest year on record, and more storms and rain are on the way for most of the country.
Flooding in Clevedon, south Auckland, in March. Auckland is heading for its second wettest year on record, while Tauranga and Christchurch have already recorded their usual annual rainfall. Photo: RNZ / Brad White
Auckland, Tauranga and Christchurch have already recorded their usual annual rainfall with just under four months of the year still to go.
National Institute of Water and Atmospheric Research (NIWA) forecaster Ben Noll said Christchurch had had almost four times the rain this winter than last, while Auckland was tracking for the highest rainfall since its wettest year on record in 1979.
Flooding in Christchurch in July Photo: RNZ / Sebastian Beyrer
"It's been an impressively wet start to the year 2017 across the country and there's more to come" - NIWA forecaster Ben Noll
This year's sodden weather has been partly due to warmer than average sea surface temperatures around and to the north of New Zealand, increasing the amount of water vapour in the atmosphere.
"It can influence storms, as they track over these warm waters and then often can dump rain on New Zealand.
"So patterns in the ocean and atmosphere are working together to create what has been a very wet start to the year so far.
Properties near Oamaru were deluged by floodwaters in July. Photo: RNZ / Rebekah Parsons-King
New Zealand was in a "La Niña-like" pattern tending to produce more wind from the north, which also brought more moisture in the air.
Mr Noll told Morning Report storms would continue to track in from the north over the next three months.
But New Zealand's rainfall, though flooding houses and farms and closing roads, was much less than the "mind boggling" deluge in Houston, Texas.
Mr Noll said Tropical Storm Harvey dropped 1270mm of rain around Houston in five days; that was more than two years' rainfall for Christchurch, and more than a year's worth of rain in Auckland.
"It puts our wetness in perspective a bit."
NIWA is forecasting rainfall totals are likely to be either normal or above normal for the North Island and the north of the South Island over the next three months, and near normal for the rest of the country. Temperatures are likely to be above normal.