Civil defence is on high alert in South Canterbury tonight as heavy rain hits the region.
Rivers are bursting, washing out roads and bridges and wreaking havoc on local livestock.
Between 120 to 189mm of rain has already fallen, according to Civil Defence.
South Canterbury foothill rivers and catchments are flowing at a 10 to 20 year high after more than 24 hours of rainfall.
Some farmers have already lost new season lambs.
Farmer John France, said: "I'm up against it.
"I'm just shifting them out because tonight's gonna get flooded out over here. So I'm just taking them home to higher ground."
Residents at the Pareora River Huts have been warned that rising rivers could mean they might be forced to evacuate tonight.
Paul Scott, from Whitestone Roading, told ONE News: "I haven't seen it for a long time. There's a lot of debris there which shows the river hasn't been up that high for a long time."
State Highway 8 from Fairly to Tekapo is closed due to flooding.
Driver Kurt Wieldraayer said: "Because of the flooding a wee bit further back, it's just too dangerous for the vehicles to try and get through."
Police are warning residents to avoid rivers, flood plains and river mouths.
A deep, slow-moving low to the west of the North Island is directing a strong moist easterly flow over the country.
MetService has issued heavy rain warnings for Hawkes Bay south of Cape Kidnappers, Wairarapa, eastern Marlbourough and Canterbury north of Cheviot and Canterbury Plains and the foothills between Cheviot and the Waitaki River including Banks Peninsula.
A further heavy rain warning has been issued for eastern Marlborough and north Canterbury, with MetService expecting it to stay in place until late Wednesday, with up to 150mm expected to fall about the Kaikoura ranges.
The remaining eastern areas from Cape Kidnappers to the Waitaki River should see the rain easing overnight and into early Wednesday.
Significant rainfall is expected over the Richmond Range, and also for Nelson west of Motueka from Tuesday night through to Wednesday night.
People in all these regions are advised to be aware of rising river levels and watch for localised surface flooding and slips and keep up to date with the latest forecast.
MetService said it will "continue to monitor the situation" and issue further warnings if necessary.
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