Roads are underwater and bridges have been swept away in the lower South Island after intense rain overnight caused rivers to burst their banks.
Slips blocking major roads have caused long lines of traffic, with many holidaymakers trapped across Otago and Southland.
A number of state highways are closed and motorists are being urged to avoid the areas and delay travel; more rain is forecast tonight.
In north and central Otago, campers who could move were urged to get to higher ground as waterways continue to rise.
One campervan nearly sailed out of the flooded Duntroon Domain before locals came to the rescue, towing it with a tractor.
Part of the bridge crossing the Kyeburn river has been destroyed by the flooding, washed away by the swift water.
Motorists were left trapped on the other side of the bridge at Scott Lane.
Parts of Kurow are in flood and locals say a river in Livingstone wasn't even flowing two weeks ago.
A severe weather warning has been extended until early tomorrow morning and more rain is expected to fall in already sodden areas, with thunderstorms also forecast for both the North and South Island.
But to farmer James Becker in Patearoa, there is a bright side to the rainy weather.
"This is fantastic, we've been really dry up until now... it's exactly what we need," he told 1 NEWS.