WeatherWatch is warning people in Northland and Nelson that heavy rain predicted for next week could result in heavy flooding for the two regions.
The wet weather could see as much as 100mm-200mm for the upper North Island and upper South Island, with the surrounding regions also at risk.
Long-range data could see the Nelson region get above 200mm, with 70mm in the city later next week.
The rain is being produced by a high-pressure zone near the Chatham Islands that will pull down sub-tropical air over New Zealand and block rainmakers from moving through, which can dramatically increase rainfall totals.
This wet northerly set-up then looks likely to be fuelled by low pressure in the Tasman Sea near the North Island. If it does eventuate, it could see those predicted rainfalls.
For remainder of this week, it will get colder before getting much warmer with one of the coldest weeks of the year arriving.
The South Island’s alpine high country may barely climb above freezing for the next 72 hours.
But northern NZ only has a brief stint with the cold later this week and weekend – before a sub-tropical airflow kicks in next week.
Hamilton, for example is forecast to have a low of -2degC this Friday night, but the overnight minimum will be +12degC one week from today.
