A flooded street in Ponsonby in Auckland in March 2022. Photo: Bill McKay
A Niwa weather forecaster is describing 2022's record rain as 'binge rainfall' - where a lot of rain falls in a short period of time, inundating the land.
The National Institute of Water and Atmospheric Research said 2022 was the hottest year on record - and one of the wettest.
Its Annual Climate Summary shows 2022 was the warmest year since records began in 1909, beating the previous record set the year before.
The year's annual national mean temperature was 13.76C.
This was 1.15C above the long-term average, surpassing the previous year's average temperature by 0.2C, forecaster Chris Brandolino said.
He said warmer than normal temperatures in the Indian Ocean, marine heatwaves, and climate change drove the record heat and high rainfall.
High pressure also influenced the intense weather, as well as an ongoing La Niña weather system.
Brandolino said these drivers often led to extreme weather events, which climate change was making more and more common.
"The term I like to use, maybe not the most scientific, is binge rainfall," he said.
Brandolino compared the weather to binge-watching a new season of a favourite show on Netflix, where viewers may often watch many episodes in a short timespan.
"Do you want to watch 10 episodes in two nights, or 10 episodes in 10 weeks? It's the same content, but you're squeezing a lot more into a short period of time."
The Buller River on the West Coast in flood last February. Photo: RNZ / Niva Chittock
Tristan Meyers who was the primary author of the summary said they keep track of anomalous weather patterns throughout the year in a number of ways.
He said making observations about activity in the atmosphere provided a clear indicator of extreme or anomalous weather events.
This way researchers could analyse if there was more or less water vapour in the atmosphere than expected.
Another measure, Meyers said, was observing the impact the intense weather had, such as the number of insurance claims reported after a storm.
The highest temperature last year was recorded at Lake Karapiro, which reached 34.7C on 3 January.
Taranaki received the most sunshine at 2659 hours for the year, and conversely, the Cropp River area on the West Coast saw the most rain at 11.3 metres.