Evacuations have been ordered by Civil Defence in Timaru District due to flooding, as a state of emergency remains in place.
The Timaru Distrct Council confirmed the areas to be evacuated in a post on Facebook around 3pm this afternoon.
State Highway 1 at the Rangitata Bridge and the State Highway 72 bridge, Dip Road, and Ferry Road in Arundel, and Burnham Road and Badham Road in Rangitata, remain closed.
The Rangitata River was at one point flowing at around 2140 cumecs at the gorge recorder, Timaru Civil Defence said in a statement.
The flow may reach its highest peak in the last 20 years.
Civil Defence Information Centres are currently being set up in Geraldine and Temuka.
Extreme flows expected later today will increase outflows into areas already hit by flooding, as well as increase the chance of issues developing in other parts of the river.
The extended period of very high flows is expected to significantly increase the risk of further bank erosion and breakout flows, according to Civil Defence.
Landowners with stock in low-lying areas have been advised to shift stock to higher ground as river flow patterns can change quickly.
There are indications of further heavy rainfall in alpine catchments later today and into Sunday.
It comes after slips affected several roads and power supplies were disrupted as severe thunderstorms swept through the West Coast this morning, bringing with it torrential rain and hail to the region.