The MetService is warning North Canterbury and the Kaikoura Coast are set for a drenching over the next two days.
It expects more than 250mm of rain to fall in those areas by Tuesday evening.
A severe weather forecaster, Erick Brenstrum, says the rain is likely to cause further slips and possibly flooding.
And he says it's likely to be more problematic than the heavy rain in parts of the North Island on Sunday, where some areas recorded 40 to 50mm of rain.
Mr Brenstrum says the heavy rain will be steadier in Canterbury and not as intense as what happened at the top of the North Island, but because it will last for about 48 hours it will cause more trouble.
The MetService says up to 50mm of rain fell in the Bay of Plenty on Sunday and up to 70mm in inland parts of the Coromandel.