Agriculture Minister David Carter today declared a medium-level drought zone for all of Northland, triggering relief measures for farmers, despite meteorologists saying the big dry is following a pattern likely to bring downpours early in the New Year.

"The situation in Northland is serious," said Mr Carter, who spoke to farmers and industry leaders in the region today.

"Farmers are still recovering from last summer's drought and they're now facing it all over again, weeks earlier than expected," he said.

"Even if there is a wet summer, as some weather experts are predicting, this won't change the severity of the situation as Northland has experienced its driest spring on record."

Mr Carter made the declaration covering all areas north of the Auckland Harbour Bridge despite Federated Farmers advice that history may be repeating itself and that rainfall in the region early in the New Year may be above average.

"What we are currently experiencing is a pattern similar to that seen 21 and 34 years ago," said Federated Farmers president Don Nicolson.

The National Institute of Water and Atmospheric Research (Niwa) has said the country is experiencing a La Nina weather pattern and there are indications that high-pressure systems could keep the weather dry through to Christmas.

But MetService meteorologist Bob McDavitt has advised farmers to go back and check their farm performance data for 1989 because "this La Nina is currently closest to the seasons of 1975-1976, and 1988-1989," he said.

In 1989, January was so drizzly in Auckland that people became alarmed that similar weather might strike in the summer of 1990, when the Commonwealth games were due to be staged there.

"There may well be a deja vu of all this in January 2011," said Mr McDavitt.

Mr Carter said the declaration would trigger funding for Rural Support Trusts to provide help, welfare support and farm management advice.

"I urge those who are finding it tough to seek farm management advice," the minister said. "Now is the time to look at stocking rates and feed levels, and to make the hard decisions.

"Across the country, it's shaping up to be a long summer and there is every likelihood other areas will soon find themselves in the same situation as Northland."

Mr McDavitt said the summer weather patterns in the country could be roughly divided into three zones: In the north, the easterly trade winds found in the tropics are likely to occasionally move south and bring muggy and mild conditions.

"Lows may be encouraged to form in the northern Tasman Sea and... to bring an increased amount of rain to the north," he said.

But the better-than-average summer rainfall for Northland predicted by Niwa is not expected until the second half of summer.

Northland Regional Council operations director Tony Phipps said that by Christmas the soil moisture deficit will be 100-130mm in most districts, "so we would need significant rain to restore moisture and restart pasture growth" .