The warm start to the year looks set to finally disappear, as cooler temperatures are forecast through May.

MetService's outlook for the month, released today, says fairly typical May temperatures are expected for much of the South Island, apart from Nelson and Marlborough, but the North Island's temperatures will be cooler.

"It looks likely the abnormal heat New Zealand experienced during most of the past six months has well and truly gone," MetService meteorologist Georgina Griffiths said.

The temperature dive will be driven by warm seas cooling last month, by La Nina transitioning back to neutral levels, and the Southern Ocean firing up.

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April was a stormy, changeable month and frequent lows and damaging storms affected New Zealand.


The most notable was on April 9-10, and brought low snow in the far south, heavy rain to many regions, and destructive winds peaking at 213km/h to the Auckland region.

On Sunday, another major low produced downpours between Northland and Bay of Plenty, as well as heavy rain in Nelson, along the West Coast of the South Island, and in Canterbury and Otago.

A state of emergency was declared in Ngongotaha, Rotorua, because of severe flooding.

Rotorua recorded 135mm in 24 hours, most of which fell in just four hours.

Griffiths said May would bring a brief change away from April's highly unsettled weather.

"High pressure and drier conditions prevail this week. But the weather maps soon show a variety of weather features again."

Northwesterlies return this weekend, before a mixture of intermittent lows favouring the North Island, stalled highs, and southwesterlies produce a wide range of weather conditions for the remainder of the month.

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A drier than usual May is forecast for Southland and the West Coast of the South Island.

Near normal May rainfall totals are predicted for all other regions of the country.