Level of annual rainfall in New Zealand - Data and Analysis (1975-2034)

IBISWorld estimates the annual rainfall level to remain at 1,663.4 millimetres in 2026-27, while this represents a fall of 34.6%, it is in line with the long-term average for New Zealand. Rainfall levels are highly volatile, meaning predicting them with any certainty is very difficult.New Zealand's location heavily influences its climate. According to analysis from the World Bank Group, the country's surrounding ocean, prevailing westerly winds and mountain chains lead to more rainfall in the west and drier conditions in the east. In addition, climate conditions vary between the North and South Islands, with subtropical temperatures often occurring in the country's far north. In contrast, the far south of the country has much cooler temperatures. According to NIWA, more rainfall typically occurs during the winter season in the northern and central parts of the country. Conversely, for the southern parts of New Zealand, the majority of rainfall occurs during the summer season.Annual rainfall is a highly volatile measurement. For example, the 2020-21 financial year was New Zealand's hottest year on record, with most regions across the country reporting near-normal to above-normal rainfall levels. The following year set another record for the highest average temperature, with highly volatile rainfall. Rainfall swung sharply through 2025-26. Most major cites saw moderate to low rainfall in August 2025. October then turned wetter and windier, as warmer temperatures over Antarctica strengthened the westerly winds crossing the country according to UNSW and NIWA in 2025. The second half of the year turned more extreme. In January 2026, warm tropical air brought record rainfall to the Bay of Plenty and Coromandel Peninsula, where monthly totals reached three to four times the normal level. Tauranga was hardest hit, recording 274 millimetres in a single day. A tropical storm tracking south in late March flooded Northland and the Bay of Plenty which led to emergency measures like evacuations and road closures. April stayed wet across most of the North Island, where totals topped 149% of normal, though Christchurch logged its third-driest April on record. The year closed dry, with much of the country well below normal in May 2026. NIWA attributes the volatility to warm, moist tropical air repeatedly meeting strong westerly winds. Overall, IBISWorld estimates annual rainfall to have fallen at a compound annual rate of 0.6% over the five years through 2026-27.