More than 500mm of rain is forecast for parts of the South Island this week and 100 to 150mm for the upper and western North Island as an atmospheric river or tropical rain arrives.

Stuck between powerful high pressure to the east and low pressure in the Tasman Sea, NZ has a windy week ahead with above normal temperatures and heavy rain in the north and north west of both main islands.

Australia finally sees low pressure clearing the south east this week – but only to be replaced by a very spring-like westerly change which – by Saturday – will extend from the Indian Ocean to WA, SA, VIC, TAS and eventually New Zealand by Saturday.