Cold spring ahead as El Niño tightens grip

New Zealand is facing a cold spring and dry summer as strong El Niño weather patterns persist, according to the National Institute of Water and Atmospheric Research (NIWA).

The institute's latest climate outlook said there were signs this year's event could be one of the four strongest ever recorded.

The report said the phenomenon, which increases the chance of drought in the east, heavy rainfall in the west and cooler weather, was extremely likely to continue into early 2016.

It said there was an increased risk of drought this summer in the north and east of the North Island, and the east of the South Island.

Cold weather and low rainfall are also expected for parts of the country during spring.

What's expected for spring:

• The west and east of the South Island are most likely to experience colder-than-average temperatures. Cold snaps and frosts are expected in some parts of the country from time to time.
• In the North Island and in the north of the South Island, average or below average temperatures across the season are about equally likely.
• The north and east of the North Island - Northland, Auckland, Waikato, Bay of Plenty, Gisborne, Hawke's Bay and Wairarapa - are most likely to experience below normal rainfall.
• River flows in the east of the South Island are most likely to remain low - but there are about equal chances of normal or below normal levels of rain.

Read the full report by NIWA (3 September 2015)