Forecaster Tom Adams said Canterbury was set to be slammed in the coming storm with some parts potentially getting a month's worth of rain in just 24 hours.
"At the moment what we can say with high certainty is that there is going to be a lot of rain that will reach warning criteria," said Adams.
The North Island was in the firing line as well with heavy rain and gales for the Bay of Plenty across to Taranaki north on Thursday and Friday. Central regions, still recovering from last week's snowstorm, would be pummelled for the second week running.
The rain and strong winds would start spreading across both islands on Thursday.
The south would then shiver through another cold snap with significant amounts of snow falling to 300m in Canterbury and southern Marlborough and 500m across North Otago on Friday.
As well severe southerly gales were expected to howl through coastal Canterbury and the Kaikoura coast during Friday and early Saturday.
In the North Island heavy rain is expected to fall across the upper half for the next two days with gales battering eastern and northern regions for the coming three days.
