A sudden stratospheric warming event that occurred in September had a large impact on October's weather across Aotearoa New Zealand. Displaced air masses from the sudden stratospheric warming event led to mean sea level air pressure that was lower than normal across both the North and South Island of New Zealand, with the strongest negative anomaly across the South Island. In general, high pressure was persistent to the north and northeast of the country.
This pressure gradient led to strong westerlies across the whole of New Zealand. The result was a wet and unsettled month, with multiple severe gale wind events in the east and south of the South Island and parts of the lower and eastern North Island.
Of particular note was a wind event and storm system on 23 October that caused widespread wind damage to parts of the South Island and that broke several temperature records for October. ENSO-neutral (El Niño - Southern Oscillation) conditions transitioned to La Niña during the month of October. Sea surface temperatures (SSTs) around the north and west of the North Island were mostly above average, with Marine Heatwave (MHW) conditions1 experienced mainly in the North Island.
Meanwhile across the east coast of New Zealand and the lower west coast of the South Island, SSTs cooled further, and were slightly below average for these areas.
The nationwide average temperature in October 2025 was 13.1°C. This is .94°C above the 1991-2020 October average, making it New Zealand's 10th warmest October on record.
October wasanother warm month overall for most of New Zealand. Temperatures were well above average (>1.20°C above average) in Northland, Auckland, most of the Waikato, the Bay of Plenty, Gisborne, Hawke's Bay, Taranaki, most of the Manawatū, and Wellington, and were above average (0.51-1.20°C above average) for the remainder of the North Island. For the South Island, Fiordland, parts of lower Westland around Haast, and interior Otago experienced temperatures below average (0.51-1.20°C below average), with a few pockets of Westland and Fiordland experiencing temperatures well below average (>1.20°C below average). Most of Marlborough, western Tasman, and the low country of Canterbury recorded temperatures well above average (>1.20°C above average) in October.
The high country of Canterbury, the far northern part of Otago, remaining Tasman and Marlborough experienced temperatures above average (0.51-1.20°C above average). The remaining areas of the South Island had temperatures that were mostly near average (±0.50°C of average).
Spring continued it's wet lean, as October was wet across the west and south of the South Island and across interior portions of the North Island. In the South Island, rainfall was well above normal (>149% of normal) for most of Southland, a majority of Otago, lower Westland, and inland portions of South Canterbury, and above normal (120-149% of normal) for eastern Southland, coastal Otago, much of the remaining the West Coast except near Karamea, about Banks Peninsula, and the northwest of the Tasman district. Conversely, October rainfall was below normal (50-79% of normal) in the low country of North and Mid-Canterbury, and Marlborough from Blenheim southward, with a small portion in Canterbury near Culverden experiencing well below normal (<50% of normal) rainfall in October.
In the North Island, rainfall was above normal (120-149% of normal) for most of Auckland, the Waikato except Taupō, the Coromandel Peninsula, about the Tararua Range, the foothills and ranges in the Bay of Plenty, most of the Manawatū, and northern Taranaki. Rainfall was below normal (50-79% of normal) for Central Hawke's Bay around Hastings, eastern Northland north of Whangārei, coastal Bay of Plenty from Whakatāne to Tauranga, and about Cape Palliser. Elsewhere in the North Island, near normal rainfall (80-119% of normal) fell in October.
Further Highlights:
* The highest temperature was 32.5°C, observed at Kaikōura (Middle Creek) on 23 October, and was the second highest October temperature ever recorded for New Zealand.
* The lowest temperature was -5.7°C, observed at Middlemarch on 2 October.
* The highest 1-day rainfall was 226 mm, recorded at Milford Sound on 20 October.
* The highest wind gust was 252 km/h, observed at Cape Turnagain on 21 October.
* Of the six main centres in October 2025, Tauranga was the warmest, Dunedin was the coolest, Christchurch was the driest and sunniest, Hamilton was the wettest, Wellington was the least sunny.
* The sunniest four regions in 2025 so far are Taranaki (2150 hours), wider Nelson (2126 hours), Marlborough (2105 hours), and Bay of Plenty (2083 hours).