New data released by NIWA shows some regions in Aotearoa have already recorded more than a year's worth of rain, and we're only seven months into the year.
NIWA says it was the wettest first half of the year on record for several regions in the northern and eastern parts of the North Island.
NIWA meteorologist Ben Noll said the latest data probably wouldn't surprise many Kiwis.
"Those living in Northland, Auckland, the Coromandel Peninsula, Gisborne, and Hawke's Bay have dealt with a constant barrage of sub-tropical lows, atmospheric rivers, and ex-tropical cyclones, which caused copious amounts of rainfall. It has been quite relentless."
The eleven locations across four regions recorded over a years worth of rain:
- Kaikohe (2140mm)
- Whangārei (1526mm)
- Warkworth (1525mm)
- Leigh (1234mm)
- Whangaparāoa (1114mm)
- Albany/North Shore (1319mm)
- Māngere (1152mm)
- Tauranga (1335mm)
- Gisborne (1230mm)
- Tūtira (1359mm)
- Napier (984mm)
NIWA said Kaikohe was a regions on the "rainiest end of the spectrum", receiving over 130 percent of its normal annual rainfall from January to June.
On the driest end, Waimate in South Canterbury received just 33 percent of its normal rainfall amount from January to June.
"In terms of temperature, January-June 2023 was 1.1C above average, according to NIWA's seven-station temperature series which began in 1909. This is the second warmest such period on record. Only 2016 had a warmer January-June."
NIWA explains what's behind the wet and warm weather:
La Niña: even though it officially ended earlier in the year, the lingering influence of La Niña contributed to an air pressure pattern that brought more sub-tropical, north-easterly winds, atmospheric rivers, and increased the risk for ex-tropical cyclones.
Southern Annular Mode: persistent "blocking" high pressure near the South Island enabled rain-bearing weather systems to linger for long periods of time, sometimes affecting the same regions day after day.
Marine heatwaves: frequent air flows from the north-east, reduced westerly winds, high pressure near the South Island, and climate change enabled this driver to bring warmer temperatures and increased moisture availability to the New Zealand region.
Climate change: the impact of climate change left a strong imprint on the record warmth and exacerbated the extreme rainfall events during the first half of the year.
NIWA explains what to expect:
El Niño is emerging in the tropical Pacific and is expected to bring notably different weather patterns to the country during the back half of the year as compared to the first half.
During late winter, spring, and summer, southwesterly-to-westerly winds will become more prominent. Historically, this has increased the chance for drier-than-normal conditions in eastern areas of the country and caused more rain in the west.
Noll said a change in the climate driver will see a change in the wind, and "ultimately, a likely change in rainfall patterns".
"The weather is likely to be quite different to what we've been living through in recent times."
