Niwa climate scientist Gregor Macara said the city was one of 40 locations around the country which had record or near-record high mean temperatures during winter.
Dunedin’s weather station at Musselburgh recorded a mean air temperature of 8.7°C, which was 1.4°C above normal.
The city’s previous warmest winter was last year.
Other parts of Otago and Southland that nearly broke their previous records were Oban (8.0°C), Nugget Point (7.8°C) and Tautuku (7.9°C), which had their second-warmest winters, and Oamaru (7.7°C) which had its
third-warmest winter on record.
Five of the country’s six warmest winters had now occurred since 2020.
The highest daily temperature was 25.7°C, at Hastings on June 10, and it was the second-highest temperature ever recorded in New Zealand for the winter season.
Waimate had its highest-equal daily maximum air temperatures for winter since 1908, when the mercury reached 23.4°C on June 1, and Oamaru had its third-highest with 22.2°C the same day.
The lowest temperature this winter was -11.8°C, observed at Lake Tekapo on August 3.
The highest one-day rainfall was 139mm, recorded at Arthur’s Pass on June 9.
Near-record winter extreme one-day rainfall totals were also recorded.
Roxburgh had its second-highest winter one-day rainfall total when 31mm fell on July 29, as did Tautuku when 45mm fell on June 15.
Mr Macara said because rainfall was above normal in eastern and central parts of Otago, soil-moisture levels at the end of winter were near normal for most of the region and above normal for isolated parts of Central Otago.
A more unusual record set during winter happened on July 10, when Ranfurly recorded a mean sea-level pressure of 1046.5hPa — a new national barometric pressure record.
The mean sea-level air pressure during the past winter was higher than normal over the east and south of New Zealand, Mr Macara said.
"This was associated with more easterly and northeasterly winds than normal, particularly over the South Island, with relatively few cold southerly outbreaks.
"This resulted in warmer-than-average temperatures throughout the season, with the country registering its 12th-warmest June, eighth-warmest July, and ninth-warmest August on record.
"Overall, the nationwide average temperature for winter was 9.6°C.
"This was 1.0°C above the 1991-2020 average, making it New Zealand’s third-warmest winter since Niwa’s seven-station temperature series began in 1909."
El Nino-Southern Oscillation-neutral conditions prevailed in the tropical Pacific during the season, he said.
Although an increased prevalence of easterly-quarter wind flows in New Zealand was likely influenced by an ocean-atmosphere system that was slowly progressing towards La Nina.
