Source: Earth Sciences New Zealand
By the end of September, very strong El Niño conditions were present in the tropical Pacific. Mean sea level air pressure was higher than normal over the Tasman Sea, and lower than normal to the south and east of Aotearoa New Zealand. This pattern led to more frequent southwesterly airflows across the country.
Sea surface temperatures around New Zealand were mostly near average or above average, except east of the North Island where cooler-than-average SSTs were present.
The nationwide average temperature in September 2026 was 11.0°C, which was 0.4°C above the 1991-2020 September average. The month was relatively warm for eastern and inland parts of the South Island south of Christchurch, as well as western parts of Tasman, southern Taranaki, Taupō, western Bay of Plenty, Coromandel, southern parts of Northland, and Kaipara. Temperatures were mostly near average for remaining parts of the country.
September was dry for much of the North Island, and northern parts of the South Island. In contrast, it was a wet month for much of the rest of the South Island, and southernmost parts of the North Island.
Highlights:
-The highest temperature was 24.8°C, observed at Whakatu on 27 September.
-The lowest temperature was -6.1°C, observed at Pukaki Aerodrome on 24 September.
-The highest 1-day rainfall was 154 mm, recorded at Mt Cook Village on 3 September.
-The highest wind gust was 222 km/h, observed at Cape Turnagain on 10 September.
-Of the six main centres, Tauranga was the warmest and driest, Christchurch was coolest and sunniest, Wellington was the wettest, and Hamilton was the least sunny.
-The sunniest four locations in 2026 so far are Nelson (2056 hours), Whakatāne (2019 hours), New Plymouth (1958 hours) and Richmond (1954 hours).