2020 saw MetService issue more than 300 Severe Weather Warnings issued over 50+ weather events. We’ve compiled five of
the more notable events – from the first Red Warning for Heavy Rain to the upper North Island drought.
Starting with firsts, we have the extreme heavy rain event for Fiordland, Westland and Southland that led to MetService
issuing our first Red Warning. The impact-based colour coded warning system was introduced in May of 2019 and Red
Warnings are reserved for the most impactful events which are likely to have major effects on infrastructure and
potential loss of life.
A Milford Sound station recorded over 1000mm of rain between midday Saturday 1 February and midnight Tuesday 4 February
2020. Another nearby Milford Sound station recorded 714mm over the same period, but we know that this weather station
was affected by flooding, which stopped the tipping bucket rain gauge from operating for a time. Gore (Southland)
recorded a whopping 152mm of rainfall in the same 84 hours, which is 180% of its normal February monthly rainfall total
(85mm). The road into Milford Sound was shredded by the intense rainfall with rain rates exceeding 60mm an hour. A State
of Emergency was declared on 4 February for Southland, including Fiordland and Gore. The Mataura River reached record
levels, resulting in an evacuation of Gore township.
Continuing on the extreme wet vein we have the Whangārei downpours from mid-July. After an extremely dry summer there
was a day where almost 100mm fell in a 24 hour period and just two days later 250mm fell over the same duration. Rain
rates in excess of 50mm per hour were recorded at a few stations.
Flooding was seen across the Northland region affecting State Highway 1, water treatment plants and entering many homes
and businesses in Whangārei.
A similar event, but even more localised, was seen in Napier on the 9th of November. A line of very heavy downpours
formed almost directly over the city and was ticking up large rainfall rates for hours on end. 230mm fell in the CBD
while just 5km away 130mm was recorded at the airport in the same period.
Parts of the city were heavily affected by flooding and a State of Emergency was declared.
At the other end of the scale – long term dry conditions saw the drought declared an ‘adverse event’ by the Ministry for
Primary Industries for North Auckland and Northland on the 11th of February. This was later classified as a ‘large-scale
adverse event’ covering much of northern South Island, Chatham Islands and the entire North Island. The dry run
continued into winter for many of the regions.
A station in Ruakura, Hamilton had its driest summer since records began in 1905 with just 91mm of rain. It was also the
2nd driest summer on record for Tauranga (88mm), in observations since 1898. It was the 2nd driest summer on record for
Whangarei (70mm), in records since 1937. Only the drought of 1945/46 was drier (55mm). Many gauges in Auckland
experienced the driest or 2nd driest summer on record.
The end of September saw an intense low pressure system cross over the country bringing heavy rain and strong winds to
much of New Zealand. As the low moved away to the east a very cold southerly airflow moved up the South Island unlocking
the potential for snow to fall to low levels.
Snow settled at sea level around Stewart Island, Southland and even fell on the beaches of Dunedin City. As the cold air
moved northwards snow fell at less common locations like Reefton and St Arnaud.
While this is not a comprehensive list here are some other notable weather events:Wellington South Coast Swell 15/04/20Christchurch Airport went 7 days with no recorded sunshine 29/06/20Auckland Harbour Bridge extreme wind gust 18/09/20Christchurch heatwave 17/11/20New Plymouth Flooding 25/11/20Plimmerton Flooding 29/11/20Kelburn, Wellington 2nd dimmest/wettest November on recordSevere hail storm in Motueka 26/12/20
No doubt 2021 will have its fair share of adverse weather and we’ll be right alongside issuing the official Severe
Weather information for all inhabitants of New Zealand. MetService is operating 24/7 every day of the year to keep you
up to date on impending weather so you can make informed decisions and remain safe.