Earth Sciences New Zealand’s Seasonal Climate Outlook for February to April 2026, released on Feb. 2, states that weak La Niña conditions remain present in the tropical Pacific but are expected to continue weakening over coming months. The organisation reports that its Relative Oceanic Niño Index has eased, and it estimates about an 80% chance that El Niño–Southern Oscillation (ENSO) conditions will return to neutral by the end of the three‑month period.
Forecasters expect higher‑than‑normal pressure south of New Zealand and lower‑than‑normal pressure to the north, favouring an easterly‑quarter airflow over the country. Early February is expected to see slow‑moving high‑pressure systems bringing settled spells, interrupted by shorter unsettled periods. From around mid‑February, the likelihood of systems drawing moisture from subtropical and tropical regions is expected to rise, including the possibility of ex‑tropical cyclone remnants tracking close to or over New Zealand. The southwest Pacific tropical cyclone outlook for the November 2025 to April 2026 season indicates a normal to elevated risk of ex‑tropical cyclone interaction for New Zealand, with northern areas typically most exposed in late summer and early autumn.
For February to April, Earth Sciences NZ’s guidance includes:
Earth Sciences NZ notes that, as the season progresses, systems linked to the tropics and subtropics may drive significant rainfall events, particularly across the North Island, even where seasonal totals are forecast to be near normal when averaged over three months. Soil moisture and river flows are forecast to be near normal or above normal for the north and east of the North Island and the east of the South Island. Most remaining regions are expected to sit near normal, with the west of the South Island showing roughly even chances of below‑normal or near‑normal river flows.
Sea surface temperatures (SSTs) around New Zealand declined sharply in January under the influence of deep low‑pressure systems, bringing an end to marine heatwave conditions close to shore. Month‑to‑date coastal SST anomalies, however, remain positive. Earth Sciences NZ expects La Niña’s lagged influence, which tends to favour warmer‑than‑average coastal SSTs, to re‑emerge, with coupled ocean–atmosphere models indicating a tendency toward above‑average SSTs across the February–April period.
The seasonal outlook coincides with national flood‑risk research led by Earth Sciences NZ, which estimates that more than 750,000 people currently live in locations exposed to flooding from one‑in‑100‑year rainfall events. Under a scenario of 3°C additional warming, that figure is projected to exceed 900,000. The study estimates that buildings exposed to such events currently represent around $235 billion in value, increasing to a projected $288 billion with 3°C of further warming. The research also quantifies exposure of key infrastructure, including approximately 26,800 kilometres of roads, 14,100 kilometres of stormwater pipelines, and 21% of national grid sites under the current climate, with all three figures rising in higher‑warming scenarios.
According to the research, regional exposure varies from about 8% of people in Taranaki to 34% on the West Coast being exposed to one‑in‑100‑year rainfall events under current conditions. The findings draw on a five‑year programme on flood risk involving multiple research organisations, universities, councils, central government agencies, and industry partners. One output is a nationally consistent flood hazard viewer that applies a single method to map 1% annual exceedance probability rainfall flooding across 256 flood plains. The tool includes mapping for the current climate and for +1°C, +2°C, and +3°C warming scenarios.
For insurance professionals, the combination of a wetter seasonal signal over parts of the North Island, an ongoing chance of ex‑tropical cyclone remnants affecting New Zealand, and quantified national exposure to rainfall flooding has implications for underwriting, accumulation management, and capital planning. Vero’s Climate Change Scenario Analysis indicates that, in the absence of substantial mitigation, physical climate risks such as floods, storms, and coastal inundation are projected to increase by 2050. The analysis suggests that losses are unevenly distributed: less than 1.5% of present‑day insured coastal properties are projected to account for all modelled coastal inundation losses, while fewer than 2% of inland properties account for about 30% of projected flood‑related losses.
At portfolio level, the analysis projects that average annual loss from extreme weather events could rise by 19% to 26% by mid‑century. Accelerating sea‑level rise and more intense surface‑water flooding, particularly in parts of the South Island, are identified as key contributors. Taken together, the seasonal guidance, flood‑hazard mapping, and scenario work are likely to inform insurers, intermediaries, and regulators as they reassess flood‑related coverage, pricing, reinsurance structures, and long‑term adaptation and resilience strategies in New Zealand’s general insurance market.
