Last month was the coldest January recorded since 2017, according to NIWA.
NIWA released its monthly climate summary today, noting the nationwide average temperature was 16.4C last month — the same average temperature as January eight years ago.
Below-average temperatures were recorded in the central and southern North Island and much of the South Island.
Six locations — Martinborough, Māhia, Winchmore, Waipara West, Diamond Harbour, and Le Bons Bay — recorded their coldest January on record. A further 17 locations experienced near-record-low mean temperatures for January.
Waiau was New Zealand’s coldest location, with its 50C mean temperature that was 3.1C lower than normal.
NIWA said a contributor to the temperature drop was lower than normal mean sea level pressure from the east of New Zealand, resulting in more southeasterly airflows than usual.
“Regular spells of southerly winds meant daily maximum temperatures below 20C were a common occurrence for eastern parts of the South Island and southern parts of the North Island,” the report said.
While much of the country experienced lower-than-average temperatures, some had above-average temperatures.
Western parts of the South Island, including the West Coast and Fiordland, experienced above-average warmth. New Zealand’s warmest location was Greymouth, with a mean temperature of 17.6C being 1.8C higher than usual.
NIWA said the “unusually high” frequency of southeasterly winds caused the southern Alps to create a Foehn effect, resulting in a warm month for the western South Island.
“Typically, New Zealand’s prevailing westerly airflow means the Foehn effect brings relatively high temperatures to eastern parts of the South Island, but these were notably lacking during January 2025.”
The highest recorded temperature was 32.4C in Kawerau on January 24. The lowest was -0.4C, observed at Waipara River North Branch on January 25.
Dry spells on both coasts
January was also a dry month for many regions across the country. There was below-normal rainfall across the West Coast, Southland, Otago, Marlborough, Taranaki, Hawke’s Bay, Waikato, Bay of Plenty, Auckland, and southern Northland.
Oban on Stewart Island had its driest January since records began in 1975, with just 27mm of rain recorded.
The villages of Mt Cook and Franz Josef had minimum rainfall of just 14% and 19% of normal rainfall, respectively.
Rainfall totals were high for northern and eastern parts of the country, including east Canterbury, Nelson, and northern Northland.
Purerua, in the Bay of Islands, recorded 151mm of rain — 262% of normal.
The region with the most sunshine was the West Coast, basking in 328 hours. Taranaki (318 hours), Bay of Plenty (310 hours), and Mackenzie Country (302 hours) followed.
Hokitika and Greymouth hadd their sunniest January on record, under clear skies for 328 hours and 302 hours, respectively.
