"Extreme rain" causing flooding and washouts have forced evacuations in Canterbury and the closure of major sections of highway across the South Island.
A state of emergency has been declared in the Timaru district, with the local Emergency Operations Centre being activated on Saturday morning due to concerns about flooding from the nearby Rangitata River. The region was battered by rain overnight and into the early morning.
Meanwhile, there are several slips on the West Coast and rising lake water levels in Otago.
Live updates are now over.
7:45pm - The Timaru District Council has been sharing some places displaced residents and tourists may want to try for accomodation.
The Winchester Bridge Campground is said to have a lot of space for self-contained campers while the Hibernian Hotel is letting people with trucks and campervans park up at their establishment. A shower and toilet is also offered.
7:15pm - Photos have been shared online of a large slip on Mt Hercules on the West Coast as well as debris on roads.
7pm - NIWA has shared a video showing the forecasted rain for Sunday. After striking the South Island on Friday night and Saturday, the majority of the downfalls look to centre on the lower North Island on Sunday.
6:30pm - The river flow is expected to peak at around 7pm - possible at 3000 cubic metres a second. That would be the highest in 20 years.
That has some locals worried. Katie Pierce is a dairy farmer on the southern side of the river. Her partner is also a dairy farmer, but he is on the other side of the river.
"The water is heading towards him now and we can't get to him," Pierce told Newshub.
6:15pm - Stay Timaru is offering a free coffee, shower and towel people displaced by the evacuations.
"We believe some people are unfortunately staying in their vehicles tonight due to no acomodation. We are also fully booked, however would like to offer anyone stuck the opportunity to have a nice hot shower, a coffee, and somewhere to relax for an hour or so."
6:05pm - Incredible video footage sent to Newshub shows a cliff slip creating a tsunami along the Rangitata River.
5:35pm - The Timaru District Council is telling residents of Rangitata Island - the area closest to the river by State Highway 1 - to now stay put if they have remained at their houses.
Earlier, the council said residents in the area should evacuate, but there were reports by some that the surrounding streets were blocked.
4:55pm - Astonishing photos and videos are emerging of the aftermath of the torrential rain and the impact flooding continues to have.
4:45pm - Rangitata's local MP, Andrew Falloon, has tweeted that most of Rangitata Island Rd is under water.
4:40pm - NZTA advises that State Highway 6 between Hokitika and Makarora remains closed. An assessment of the road has been done and the section between Haast Pass and Makarora will reopen to one lane on Sunday at 10am. It will then close again at 4pm.
4:20pm - Fire and Emergency has taken a four-wheel-drive fire appliance out to the affected Rangitata roads to test which are still navigable, according to the Timaru council.
Residents of Rangitata Island Rd, which is the closest to the river, report being stranded.
4pm - Photos show homes affected by the Rangitata flood. Stock have been moved to higher ground where possible.
3:45pm - Residents near the affect Rangitata area have received a Civil Defence Emergency Alert warning them of the serious flooding from the river "which is still rising".
It warns residents near the river to "go to higher ground and stay with family or friends" as well as to ring 111 if they are in danger.
"Do not drive or walk through flood waters. The water may have washed away parts of the road and may contain debris. Treat all flood water as contaminated and unsafe. Stay away from flooded areas until Civil Defence gives the all-clear."
3:30pm - Heliventures NZ says it is busy doing charter flights between Oamuaru and Christchurch due to the road closures.
3:10pm - The Timaru District Council has ordered the immediate evacuation of the area between McLelland Rd and Orton Rangitata Mouth Rd.
Earlier, campers close to the river were ordered to evacuate.
"The Rangitata River is currently flowing at around 2140 cumecs at the gorge recorder and is rising rapidly. Extreme flows, likely 3000 cumecs or more, are anticipated later on Saturday," a statement at 10:30am said.
"Some floodwater is currently flowing down the South Branch, and there are several other vulnerable areas along the river that are at risk of river breakouts."
The map below shows the evacuation area.
The council said the "very high flows" may increase the risk of bank erosion and said widespread flood was "very likely".
Photos released show water flooding nearby grassy fields as well as washing onto the road. Railways have also been impacted.
Due to the widespread flooding risk, State Highway 1 at the Rangitata bridge and the State Highway 72 bridge near Arundel have been closed.
There are no diversions in place, so residents are being told to stay away. The council said the "disruption is likely to continue for the weekend", while NZTA's Pete Connors said the State Highway 72 route may not reopen on Saturday.
Civil Defence Information Centres are set up in Geraldine and Temuka.
An update from the council at 1pm said the weather had taken a turn for the better but a "significant" amount of water was still coming down the Rangitata River.
The Timaru area isn't the only South Island region affected by the disruptive weather.
Genesis Energy is alerting the public that Lake Tekapo is "fast approaching its maximum control level" due to the recent rain.
"To comply with our lake level consent conditions, water will need to flow from Lake Tekapo along the Tekapo River, via the Lake George Scott Spill Weir."
"We are currently notifying a number of parties to ensure people take care when accessing river areas in case of flow changes, do not risk crossing any river on foot or in a vehicle if there is a risk of being inundated or stranded if levels rise."
Arthur's Pass State Highway 73 between the West Coast and Canterbury is down to a single lane at Candy's Bend below the viaduct due to a major slip.
Slips in south Westland has also caused State Highway 6 to be closed from Hokitika south through the Haast Pass to Makarora. Little Man's Bridge has been washed out on State Highway 6 near Whataroa. That route will likely take about two days to deal with, NZTA says.
In Otago, there are concerns about rising water levels at lakes Wakatipu and Wanaka as well as the Clutha River. These are being monitored carefully out of concern for flooding.