April deluge: Just how wet was last month?

A Papamoa farmhouse was left totally surrounded by floodwaters during Cyclone Debbie's early April deluge. Photo / File

The final weather tallies for April have confirmed the month was as wet as it felt, with most North Island towns receiving more than twice their normal amount of rainfall.

Whangaparoa, north of Auckland, was dumped with 319mm over the month - an incredible 452 per cent of normal April rainfall - while several other places received 300 per cent of the usual amount, according to just-released official figures.

Warkworth, Whangaparaoa, Te Puke, Taupo, Martinborough, Hawera, Ohakune and Waiouru all recorded their wettest April ever, while Whitianga, Matamata, Hamilton, Dannevirke, Palmerston North, Levin, Stratford and Kaikohe came close to record levels.

Across the North Island, only northern and western Northland escaped the unseasonable deluge, receiving between 80 and 119 per cent of normal.

The highest amount of rainfall of any single day was the 186mm that doused Te Puke on April 4.

The northern and eastern South Island also received widespread rainfall in excess of 200 per cent of normal, with a couple of locations picking up more than 300 per cent of normal.

Conversely, much of the South Island's West Coast saw near to above-normal amounts and most of Southland and Queenstown-Lakes received below-normal levels.

In its climate summary, Niwa characterised April as a month dominated by higher than normal atmospheric pressure to the south and southeast of the South Island, along with lower than normal atmospheric pressure over and to the north of the North Island.

This pressure pattern resulted in more northeasterly wind flow than normal, bringing with it moist tropical air masses and record-high rainfall for parts of the North Island.

Most centres saw the bulk of their April rainfall during two events: the passing remnants of Cyclone Debbie in early April, which later led to the flooding of Edgecumbe on April 6, and the mid-month arrival of ex-Cyclone Cook, which hammered much of the North Island.

These tropical air masses also delivered very warm temperatures to much of the North Island, and further led to a very wet month for the northern and eastern South Island.

The majority of the North Island experienced well above average (high than 1.20C above average) or above average (0.51 to 1.20C above average) temperatures in April.

Of the six main centres in April 2017, Tauranga was the wettest and sunniest, Christchurch was the coolest and least sunny, Auckland was the warmest, and Dunedin was the driest.

The highest temperature was 30.3C, observed at Fernhill in Hawke's Bay on April 2, while the lowest was -2.9C, observed at Manapouri on April 7.

Of the available, regularly reporting sunshine observation sites, the sunniest four locations so far this year are Whakatane (953.3 hours), Lake Tekapo (916.1 hours), Blenheim (898.2 hours) and Richmond (886.9 hours).