South Auckland farmers say a drought in the area could not have come at a worse time with no feed heading into winter.
The drought zone in the upper North Island, which started with Northland in January, has been extended to include Waikato and the Rodney, Papakura and Manukau districts.
Papakura dairy farmer John Sexton says there has been no significant rainfall in the Auckland region since January. He says most farmers have already dried off their cows and more are following suit every day.
Further south, Waikato dairy farmer John Bluett says a lot of farmers have already dried off there too. He says it's not as bad as the drought that affected the region in 2008 because, being at the end of the season, the cows are in a better condition.
But it's still been a difficult season, Mr Bluett says, and farming through winter will be hard.
The Waikato processor and exporter Tatua expects this season's milk production to take a knock, though not as serious a one as in 2008.
Chairman Steve Allen says that with pasture cover very low he expects most farmers in Tatua's supply area to be drying off half their herds in the next 10 days. And without meaningful rain, most herds will be dried off by May - a month earlier than normal.
El Nino pattern blamed
The National Institute of Water and Atmospheric Research (NIWA) says such severe drought is likely to occur only once in a farmer's lifetime.
Principal scientist James Renwick told Morning Report that an El Nino weather pattern is to blame. He said lack of rainfall in the drought-hit areas happens only once every 30 - 40 years.
Dr Renwick says NIWA is forecasting rainfall to get back to normal towards the end of autumn, but it will take a while for soil moisture levels to recover.