New Zealand has climate zones ranging from subtropical to subantarctic. The climate is heavily influenced by New Zealand’s location in a latitudinal zone with prevailing westerly winds and by the surrounding ocean. It is also influenced by mountain chains that modify the weather systems as they sweep eastward. This leads to more rainfall in the west and drier conditions in the east. The average rainfall in most urban areas is between 600 and 1,600 mm a year. In the mountain ranges annual rainfall often exceeds 5,000 mm, and in the Southern Alps it can be more than 10,000 mm. However, areas to the east of the main ranges have an average rainfall of less than 600 mm a year. On average, most of New Zealand receives at least 2000 sunshine hours annually.
- Average annual temperatures range from 10°C in the southern part of New Zealand to 16°C in the north. Temperatures can fluctuate up to 14°C between seasons inland and to the east of the ranges, but generally the changes between summer and winter temperatures are small.
- Average annual temperature has increased approximately 1°C over the past 100 years, between 1981 – 2010.
- Extreme 24-hour duration rainfall events increased in the west of the country and decreased in the north and east between 1930 and 2004.
- An increase in heavy rainfall has been observed in western parts of the North and South Islands, while decreases have been observed in eastern regions.