Christchurch residents are being asked to stay home as emergency services become stretched amidst flooding, road closures and foul weather.
Civil Defence has also issued warnings to Te Waihora/Lake Ellesmere residents, as flooding was expected due to high water levels on Saturday.
A state of emergency was declared in Christchurch. Christchurch mayor Lianne Dalziel announced the move at midday as a "precautionary measure" to allow the region to prepare fully for any issues that may arise with the high tide due this afternoon.
States of emergency are now active in Christchurch, Selwyn, Timaru, Dunedin and Otago, after a massive storm lashed the south during the past 24 hours, causing widespread flooding.
The Selwyn District Council is warning residents to stay away from the fast-rising Selwyn River in Canterbury.
Up to 50 people are either being evacuated or are choosing to leave themselves near the river.
Police have closed State Highway 1 at the Selwyn River bridge due to flooding, with the road closed between the bridge and Dunsandel.
The council said an initial state of emergency was declared earlier this morning in the Springs Ward.
The Selwyn River has already overtopped on its northern side, and the extended declaration will cover any issues on the southern side.
River levels are anticipated to continue rising due to continuing rain, and floodwaters joining the river from higher elevations.
Council staff are also monitoring levels on the Halswell River near Tai Tapu and the Hawkins River west of State Highway 1.
Evacuations are continuing at Upper and Lower Selwyn Huts. Other residents in low-lying areas are also self-evacuating.
An evacuation centre has been established at Lincoln Event Centre.
Resident Craig Ashby, who lives just below Coes Ford, said the river had began flowing through some houses.
Mr Ashby says he and his flatmates - who are on a small farm - and a couple next door are grabbing everything and getting out in a self-evacuation.
He says they've let all the chickens out, have left the windows open and a whole heap of food for the cats.
Reports of people rubbernecking in the area are of concern - people should stay out of the area unless absolutely necessary as road conditions are extremely challenging.
The council is urging people to avoid unnecessary travel as extensive surface flooding remains over much of the district, and has urged said farmers with stock in the area to make decisions now on whether to move animals.
Precautionary boil water notices have been issued for Acheron, Hororata, Malvern Hills and Springfield.
More rain is predicted for Canterbury with up to 50mm due to fall, gradually easing in the afternoon. Much of Christchurch is also flooded, after the Heathcote river burst its banks.
