MetService's 2021 weather review: a tornado, floods and record heat

MetService has issued a look back at the significant weather events of 2021, with a tornado, heat records, and plenty of rain and floods among the extreme weather events.

Three red warning events and a tornado

MetService issued warnings for about 60 severe weather events this year, with three in the new red warning category which was introduced in 2019 to be used for "the most significant events".

One of those red warning events - the second ever issued by MetService - developed into devastating flooding on 30 and 31 May, which caused massive damages in mid-Canterbury.

A third of the area's annual rain fell in just a few days, with damages thought to be more than $19 million.

A rare tornado swept through South Auckland on 19 June, killing a man and leaving a trail of destruction. More than 1200 homes were affected, with 60 declared uninhabitable in the aftermath.

Then 2021's second red warning was issued in mid-July, for heavy rain in Westland and Buller, and warnings for people in low-lying areas to prepare to evacuate.

Heavy rain fell across a large portion of the north of the South Island, up to 200 - 500mm in just a few days in some places, and damage from wind was also felt in parts of the North Island.

In Westport, the deluge caused flooding that left more than 500 homes uninhabitable or needing cleaning out and repairs after the storm, and repairs are still continuing to the major damage caused to Marlborough roads, with some parts still closed.

On 8 August, a storm brought widespread gales to much of the country, and heavy snow in the South Island; "Roads and schools were closed, trampolines went flying, powerlines were downed, and Wellington even saw a very light, very brief flurry of snow," MetService said.

In late August, another storm caused flooding in Kumeū and other parts of Auckland, with homes and businesses flooded, and emergency services reporting they had received more than 370 calls for help.

"Around 200mm of rain accumulated [in Kumeū] in a 24-hour period, while nearby Whenuapai saw 100mm. The localised nature of this intense band of rain was highlighted by the fact that Auckland Airport didn't even record 20mm of rain during the time," MetService said.

In September the third red warning came, this time for strong winds; "and extreme example of the 'roaring forties'", the agency said. The storm contributed to large power outages, caused car crashes, lightening strikes caused fires, and caravans were tipped on their side.

In November, Gisborne was drenched with persistent, heavy rain; "Ticking up three times their normal November rain in the space of 48 hours, with about another month's worth [of rain] falling in the next three days." Flooding was widespread, with evacuations, landslides, and dumps of silt through residential streets, and a state of emergency was declared.

Te Araroa and East Cape also experienced flooding in December.

Temperature records

Central Otago had an "incredibly wet start to the year" in 2021, MetService said, with about twice January's normal rain falling in one day at Alexandra airport. The deluge caused widespread disruptions for travellers in the wider region.

Canterbury's January was so hot that health warnings against overheating were issued by authorities. Weather stations at Ashburton and Christchurch airports broke heat records in late January, recording 39.3C and 37.1C respectively.

Timaru had its coldest May temperature, reaching -7.8C.

Whangārei, Auckland, Hamilton, Tauranga, and Taupō all recorded their warmest November on record.

Southern parts of the North Island had a soggy start to summer. Paraparaumu had a record wet December, with 300mm of rain by 17 December - the suburb's previous average for the month was close to 70mm.

And Wellington broke its record for strongest wind gust on 20 December at the Kelburn weather station, at 133km/h.