Last month was the wettest June on record for Central Otago and coastal areas of Canterbury, while storms wreaked havoc across much of the country.
A 202kmh wind gust at Mt Kaukau in Wellington on June 20 was the strongest recorded at the site in any June, Niwa said in its climate summary for the month.
A 143kmh gust at Wellington airport was also a June record, as was a 126kmh gust at Whanganui, a 120kmh gust at Mangere in Auckland, and a 78kmh gust at Wanaka.
Extreme weather during the month included torrential rain in Nelson and Tasman that caused a 200-metre long slip near Kaiteriteri that destroyed a house and resulted in the death of 63-year-old Jude Hivon.
Flooding also closed transport routes in and out of Dunedin and Oamaru, while the worst flooding of Lake Ellesmere in decades put thousands of hectares of farmland under water and forced the evacuation of some homes.
The severe gales which hit Wellington caused loss of electricity to 30,000 homes, and airline, train and ferry services were cancelled. The storm of June 19-21 brought the strongest sustained 10-minute winds at Wellington airport since 1985.
Snow was unofficially at least 60 centimetres deep in Tekapo, Naseby, Clarks Junction and the Hakataramea Valley during a "severe snow event" on June 20 and 21, Niwa said.
Staff at Mt Hutt in Canterbury estimated 2.8 metres of new snow from the storm, with drifts of more than 6m on the access road.
North Otago, south and mid-Canterbury had more than 400 per cent of the normal June rainfall. Parts of South Otago, Central Otago, the Mackenzie Country, North Canterbury and Marlborough had more than 200 per cent of normal.
The 220 millimetres of rain that fell at Riccarton in Christchurch was a record for a June month and 376 per cent of normal. Lincoln had a June record 209mm, 365 per cent of normal, while the record 116mm in Ranfurly was 384 per cent of normal.
In Dunedin the 171mm of rain was 296 per cent of normal and the second-highest June rainfall on record.
Motueka had its second-highest June one-day rainfall total with 141mm recorded on June 16, while Riccarton had its third-highest June one-day total with 69mm.
Sunshine hours were the lowest on record for June at Blenheim, where the 111 hours were 75 per cent of normal. The 62 sunshine hours at Cromwell were the second-lowest for June at 70 per cent of normal.
Last month was characterised by lower pressures than normal across the country and to the north and northeast. High pressure centres persisted to the south and southeast of Tasmania, Niwa said.
The result was an anomalous east-southeasterly flow over the South Island, which contributed to well above-normal rainfall totals throughout areas to the east of the Southern Alps.