An area of lower air pressure over the Tasman sea is slowly approaching New Zealand.
Between this area of low pressure to the west and a high pressure system to the east, sub-tropical northerly winds dominate over the entire country.
It’s this air flow that will see Southland reach 30 degrees on Sunday and Monday and overnight lows in northern New Zealand possibly not below 20 degrees for some with high humidity.
Stray thunderstorms are likely in the North Island mainly in interior areas on Saturday and Sunday. Some storms may be severe and could produce flash flooding.
Temperatures are markedly warmer than usual in the South Island until Tuesday.
– WeatherWatch.co.nz (maps by The Weather Company, an IBM business)