Despite being downgraded, ex-tropical Cyclone Uesi is still powerful and communities in the lower South Island are being warned to brace themselves.
And it could bring some much-needed rain to the drought-stricken North Island later next week, says WeatherWatch.
The low pressure system is likely to hit the lower South Island on Sunday, bringing with it intense rain, a burst of gales and dangerous seas.
MetService meteorologist Andrew James said communities in the West Coast and potentially Southland and Otago should prepare for heavy rain.
• Cyclone warning: Ex-tropical cyclone Uesi on track to bring heavy rain to South Island
• Cyclone warning: Uesi set to bring heavy rain, gales, to the south
• Big Dry: Parched north faces 'cyclone lottery'
• Big Dry: No rain in sight for drought-parched north
A severe weather outlook has been issued by MetService detailing significant heavy rain and severe east and northeast gales for the Southern Alps, West Coast, Otago and Southland for Sunday and Monday.
Another update is expected this morning.
WeatherWatch said much of the storm will likely stay at sea and only part of it will hit the South Island on Sunday - but it will be enough to dump 150mm of rain in 24 hours on the West Coast and bring waves of up to eight metres.
"Storm surge and large waves have the possibility to cause coastal erosion and possibly cause some coastal flooding, especially around rivers in New Zealand later on Sunday and into Monday," Weather Watch said.
But while it is set to miss the North Island, WeatherWatch said the "leftovers" might bring some welcome downpours to the drought regions.
"Showers, by definition, are off and on and hit and miss - so not everyone will be lucky enough to get some rain. But in New Zealand some of our droughts get fixed this way, by repetitive afternoon downpours rather than a low bringing rain."
WeatherWatch said the downpours will be inland for the most part, but may drift to some coastal areas later.
"They will mostly form through Waikato and Northland and towards Gisborne and Hawke's Bay with next Tuesday, Wednesday and Thursday perhaps the best opportunities."