The Metservice has issued an orange rain warning for parts of Canterbury, including the plains north of Ashburton, the foothills, and in and around Christchurch, from 1am Wednesday to 6am Thursday.
"Expect 110mm to 160mm of rain to accumulate, especially north of Christchurch. Peak rates of 15 to 25 mm/h. Note, heavy rain is expected to ease north of Christchurch after midnight Wednesday," the Metservice said.
"Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous."
Tasman, Motueka and Eastern Marlborough are also all under a heavy rain warning from 1am to 4pm on Wednesday.
The Kaikoura coast is predicted to be the worst hit area with 100-180mm of rain expected to fall.
Meanwhile, Metservice has a heavy rain warning in place for the Tararua Ranges with 20-30mm of additional rainfall expected to hit the area.
State Highway 1 was down to one southbound lane just north of Paekakariki on Tuesday because of flooding.
Grays Road between Plimmerton and Pauatahanui was closed due to flooding. Paekakariki Hill Road was also closed due to a slip.
In the upper North Island, a heavy rain warning is in place for Bay of Plenty and Coromandel Peninsula. Bay of Plenty could see between 150-220mm of rain in inland areas, especially about the Eastern Ranges.
The Metservice warns rain may cause streams and rivers to rise rapidly, while surface flooding and slips were also possible.
- Additional reporting RNZ
