It was a warm and dry June for many regions but wet and cold in others according to NIWA's latest climate summary, which revealed some historic highs and lows.
Eight locations observed their warmest June on record. Perhaps most notably, Christchurch (Botanic Gardens) and Lincoln observed their highest mean temperature for June, with records beginning in 1863 and 1881, respectively.
NIWA climate scientist Gregor Macara told 1News "a lot of areas are seeing really enhanced temperatures".
"Right now sea surface temperatures are above normal, we are still observing marine heatwaves and climate change going on in the background.
"There's usually winners and losers when it comes to climate at the moment and those western and southern parts of the South Island have been doing well and have had a reasonable start to the year," Macara said.
NIWA's report revealed warmer than average sea surface temperatures contributed to the high air temperatures for much of New Zealand in June, with marine heatwave conditions present in coastal waters near the South Island and lower North Island.
New Zealand's coolest location relative to normal was Lauder (Central Otago), where the mean temperature of 2.1C was 1.2C below the June normal. This included a period of nearly five consecutive days where the air temperature remained below freezing.
It was a particularly dry month for Manawatū-Whanganui, Kāpiti Coast, and parts of Wellington and the Mackenzie Basin, where less than 25% of normal June rainfall was recorded. Most notably, Paraparaumu and Pukaki Aerodrome recorded their driest June on record, with just 7mm and 2mm of rainfall for the month, respectively.
In contrast, it was yet another wet month for Gisborne, Hawke's Bay and Northland. Seven locations observed record or near-record high rainfall totals for June. With 303mm, Gisborne recorded 282% of normal June rainfall, making it the city's second-wettest June since 1905.
Temperatures were well above average or above average for most of the main centres. The exception was Auckland where temperatures were near average. It was a wet June for Hamilton and Tauranga, where rainfall was above normal and well above normal, respectively. In contrast, it was dry in Wellington where just 47mm of rainfall (35% of normal) was recorded, making it the city's fourth driest June since records began in 1928.
From January 1 to June 30, 2023, Auckland recorded 1151mm of rain. This is 44mm more than Auckland's annual average rainfall total. Of the six main centres in June 2023, Tauranga was the warmest, wettest, and sunniest, Christchurch was the coolest, Wellington was the driest, and Dunedin was the least sunny.
NIWA develop comparisons based on climate normals, which are three-decade averages of weather variables, such as temperature and precipitation.
"We use our climate normal to characterise what we would expect in at a given location at a given time of year," Macara said, although he explained that climate change is complicating what is considered "normal".
"It's hard to keep up with what is normal as those air, sea and earth temperatures are increasing at different rates across the globe, because the globe overall is warming.
"It's also observed in our ice resources so that's a real big one in New Zealand. We are seeing a massive decline in the ice glacier size in most places around the world — we are losing snow and ice."
Macara said glaciers are good indicators of climate change because they are affected by precipitation (rain, hail and snow), sunshine and temperature. He said they are measured in a survey of 50 glaciers which are all photographed annually.
"In that time we've seen some considerable decreases in all of the glaciers. The Fox and Franz Josef Glacier hit a period when they grew in length but have now significantly retreated."
Macara said "the entirety of the Southern Alps and Mount Ruapehu are getting smaller".
Snow and ice
On June 5, snow fell and settled to approximately 400m above sea level in parts of Central Otago. The Lindis Pass (SH8) was temporarily closed due to snow, according to the report.
On June 19, Mount Hutt ski area (Canterbury) was forced to close due to a lack of snow, after opening for the season on June 10. The snowpack depth was relatively low to start the season, and warm temperatures combined with a period of rain meant the lower elevation runs became unskiable.
Farther south, Coronet Peak (Otago) opened their learner area and Meadows Chair on June 16, but the ski area was also forced to subsequently close on June 26 due to deteriorating conditions and a lack of snow.
Lightning, hail, and tornadoes
On June 1, approximately 8000 lightning strikes were recorded over the West Coast of the South Island. On June 5, thunderstorms occurred over upper parts of the North Island. A funnel cloud was sighted off the coast of Langs Beach, Northland. Farther south, approximately 500 lightning strikes were detected near the Coromandel Peninsula.
Cloud and fog
For much of June, but especially June 6 to 25, high pressure persisted over much of the South Island. This resulted in an inversion becoming established, with low cloud and fog trapped in many inland valleys and basins. Cromwell was one location subject to persistent low cloud cover, with the town receiving just 54 hours of sunshine for the month — its lowest sunshine total for June since records began in 1979.
Highs and lows
- The highest temperature was 24.0C, observed at Whakatu on June 2.
- The lowest temperature was -10.6C, observed at Tara Hills on June 10.
- The highest 1-day rainfall was 109mm, recorded at Mt Cook Village on June 1.
- The highest wind gust was 161km/h, observed at Puysegur Point on June 1.
- Of the six main centres in June 2023, Tauranga was the warmest, wettest, and sunniest, Christchurch was the coolest, Wellington was the driest, and Dunedin was the least sunny.
- Of the available, regularly reporting sunshine observation sites, the sunniest four locations in 2023 so far are Taranaki (1248 hours), Mackenzie Basin (1240 hours), West Coast (1210 hours) and wider Nelson (1201 hours).
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