Drier in the East, Wetter in the West
The overall projection is for 5-10% less rain in most of the east coast and north of the North Island, coastal Canterbury & coastal Marlborough, and for a wetter climate in the west and south of the South Island by the end of the century.
In addition, different seasons could see different rainfall patterns.
In winter and spring, more frequent and possibly stronger westerly winds appear likely, especially over the South Island. This would bring drier weather in the east and north, but more rain in the west of both islands.
In summer and autumn, the projected pattern is less clear-cut, but tentatively points to less frequent westerlies. This suggests slightly drier summers and autumns in the west of North Island, and possibly wetter conditions in Gisborne and Hawkes Bay for those seasons.
In addition, there are implications for extreme rainfall events. Heavy rainfall is likely to get heavier and/or more frequent. For a mid-range scenario, a 1-in-100 year 24-hour heavy rainfall event now could become a 1-in-50 year event by the end of the century.