Farmers living in areas that are increasingly becoming drought hot spots will have to prepare for drier times ahead, a climate scientist says.

Research co-authored by Auckland climate scientist Dr Jim Salinger analysed records going back to the early 1940s and defined five regions for their drought variability.

Four areas — the north and east of the South Island and the west and north of the North Island — showed a distinct trend towards increased drought over the 70-year period.

"In these trends we are seeing a drying over the 72 years in four out of five of these drought hot spots," Dr Salinger said. "Certainly, what we are seeing is a trend toward a drying in summer in the North Island, and we are seeing this in the western North Island in areas from Waikato to Manawatu, which are usually well watered.


"Farmers will really need to look at management and water storage, and what sort of carrying capacity, and the type of farming activity that their pastures will support."

Most of Northland's west coast, from Cape Reinga to Pouto Pt, is in a "pocket drought" which the Government has declared a localised adverse event.

The classification covers 400 Northland dairy farms and 700 sheep and beef units.

Federated Farmers Northland provincial president Roger Ludbrook said there had been a "hangover" from last year's drought among some farmers in the west of the region, who hadn't had enough spring growth.

Dr Salinger said the concerning chances of an El Nino developing by spring — put at 50 per cent by the National Institute for Water and Atmosphere — also posed the question of whether dry areas may see their third drought in three years.

"We'll know by mid-to late winter if it is definitely happening."

Drying out

• North of the South Island
• East of the South Island
• West of the North Island
• North of the North Island