Dozens of Canterbury properties were flooded by heavy rain overnight.
A Fire Service spokesman said there were 39 weather-related calls from the region between about 10pm and 2am, mostly for surface flooding.
The incidents were mostly around Lyttelton and Sumner, already sodden after several periods of heavy rain in the past month.
A property in Rangiora also had to be evacuated due to flooding.
Firefighters had helped about six people from the Mairaki Rd house and organised motel accommodation for them.
MetService severe weather forecaster Eric Brenstrum said about 100mm of rain fell in parts of the Canterbury Plains overnight, and a bit more than that in Banks Peninsula.
The heavy rain was expected to continue in the region today but would probably clear tomorrow.
A MetService severe weather warning remains in place for Canterbury and Otago.
In the Far North, firefighters have had to deal with the aftermath of a suspected tornado overnight.
Fire Service northern communications centre shift manager Jaron Phillips said at 9.45pm emergency services received reports of a tornado near Taipa, about 40km north-east of Kaitaia.
"Apparently five trees were knocked down - one very large tree - and were completely blocking State Highway 10."
Firefighters and roading contractors used chainsaws and a digger to remove the trees.
The road has since reopened.
Mr Brenstrum said there was a burst of heavy rain and thunderstorms in the area last night, which would be consistent with a tornado.
Snow is also effecting roads in the upper South Island.