Northland dairy farmers are bracing for their fifth drought in seven years.
MetService has warned the country will start to feel the bite from an intensifying El Nino weather pattern in the lead up to Christmas, with the most effect to be felt in January and February.
Apart from being hit by four droughts in the past six years, Northland farmers were also hit by severe flooding in July 2014.
The last El Nino weather phenomenon to strike the country was in 2010. El Nino is a climate pattern associated with unusually warm ocean waters in parts of the Pacific Ocean. In New Zealand, an El Nino event could make western areas wetter, and the eastern seaboard drier than usual.
The Northland Rural Support Trust has advised farmers to prepare well in advance by having supplements ready and to seek help from financial institutions such as their banks and the Inland Revenue Department in terms of deferring their loan payments and tax obligations.
MetService meteorologist Georgina Griffiths said rainfall in Northland was likely to drop from an average 260mm in summer to about 180mm, which would be a significant decrease at a dry time of the year.
"For farmers, it's a heads-up ... a monitoring phase so they don't get worried too early but they need to monitor this El Nino."
Trust co-ordinator Julie Jonker said while an El Nino threat was present, it depended on how the weather pattern manifested itself between December and February.
She has urged farmers to proof themselves as much as they can from the effects of drought by making supplements well in advance of summer.
"In summer if we get small, regular rain, that will help. Farmers do need to take precaution, especially since a low dairy payout has stressed them.
"It all depends on how the El Nino manifests because we've had, in the past, light and severe effects as well as south-westerly showers so we can't make any predictions on how this will unfold," she said.
Dairy farmer Denis Anderson, vice-president of Federated Farmers' Northland, said any drought on top of the recent low dairy payout would be disastrous.
"The last drought cost each farmer between one to two dollars less per kilogram of milk solid and there simply isn't enough extra money available to fund another drought."
Mr Anderson said though the winter rain helped in the growth of enough feed, it may not last for spring or until summer.
Primary Industries' Minister Nathan Guy said he would be keeping a close eye on weather in Northland and the rest of the country.
"The Government has also allocated $75,000 towards a study to investigate the potential of irrigation in Northland, which can help farmers and growers cope with dry conditions."
Parts of the Pacific Ocean are now the hottest they have been in 17 years, with sea temperatures across the eastern half of the Pacific more than 2C above normal.
MetService said the country has already seen solid signs of El Nino so far this winter with more frequent southerly outbreaks than usual which have resulted in below average temperatures since the middle of June.
Seas around the coastline are also colder than usual, particularly off the East Coast such as Whangarei.
El Nino will likely continue into early 2016, and there is every indication it will remain strong for the rest of the year.