A nasty weather system has caused chaos across the country - particularly in the coastal areas of the South Island, with widespread flooding.

Several hundred people have been evacuated across the South Island, with states of emergency still in place for Dunedin, Otago, Christchurch and Selwyn.

The state of emergency in Timaru was lifted on Saturday afternoon.

Here's what you need to know:

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WEATHER

Canterbury, North Otago and Dunedin are subject to heavy rain warnings.

Canterbury - Heavy rain should ease late afternoon and evening. In the 10 hours from 9am to 7pm today, a further 30 to 50mm is expected to accumulate on top of what has already fallen, especially about the foothills and ranges. Peak intensities of 5 to 10mm per hour. Rain falling as snow above 800 metres.

North Otago - Heavy rain easing by afternoon. In the 5 hours from 9am to 2pm today, expect 15 to 25mm of rain to accumulate in addition to what has already fallen, especially about the hills and ranges. Peak intensities of 5 to 10mm per hour. Rain falling as snow above 600 metres. Dunedin - Heavy rain is expected to continue until late Saturday morning. In the 12 hours from 9pm today to 9am Saturday, expect 40 to 50mm of rain to accumulate in addition to what has already fallen. Peak intensities of 10 to 15mm per hour.

Dunedin - Heavy rain gradually easing by this afternoon. In the three hours from 9am to midday today (Saturday), expect 15 to 20mm of rain to accumulate in addition to what has already fallen. Peak intensities of 5 to 10mm per hour.

Strong wind warnings have been lifted for Westland and Fiordlands

Flooding at Long Beach Dunedin. Photo/ Ben De Haan
Flooding at Long Beach Dunedin. Photo/ Ben De Haan

EVACUATIONS

Christchurch residents near the Heathcote river are urgently being asked to evacuate their homes as high tide, scheduled for 3.15pm, was anticipated to cause "significant flooding".

In particular residents at Clarendon Terrace, Richardson Terrace, Hunter Terrace, Eastern Terrace, Riverlaw Terrace, Palatine Terrace, Ford Road near Louison Place and Waimea Terrace were expected to be affected, and anybody in low lying areas.

People who couldn't be with family or friends were told to go to Lindwood College where Civil Defence had set up a centre.

Residents were warned that if water was above knee level around their homes, the current could be dangerous, and people should stay in their houses and wait for help.

Response teams are out in boats and the army was providing support.

Twelve houses have been evacuated due to a slip on Ravenswood St in St Clair.

The second largest flood on record is impacting communities in the Taieri River catchment.

Civil Defence has evacuated several rural properties in the Mill Creek area, Taieri because of concerns about the structure of the pump station due to high river flows.

Flooding in parts of Mosgiel and the Taieri Plain has meant some residents have been evacuated.

Overall, about 220 homes were evacuated overnight across the region from Oamaru to Milton and inland to the Ida Valley. Around 100 of those are in Outram near Dunedin airport.

About 50 people have evacuated near Selwyn.

FLOODING

Surface flooding has affected roads around Dunedin and forced some residents, in areas such as lower Outram, Mosgiel and the Taieri, to evacuate.

Rain was still falling steadily in most places this morning with MetService predicting another 30-50mm could fall in North Otago today. Group Controller Scott MacLean said that at one Dunedin site, 225mm of rain fell in less than 24 hours, compared to the average rainfall of 45-50mm for the whole of July. Heavy snow is also now predicted for inland Otago later today.

Dunedin Civil Defence Controller Sandy Graham says from yesterday morning to 7am today, about 223mm of rain was recorded at Swampy Spur, and 114mm at Riccarton Rd near Mosgiel. Musselburgh had recorded about 81mm.

"People need to be aware there will be widespread debris and damage on roads, and motorists will not be able to tell the depth of floodwaters. Avoid non-essential travel today and do not go rubbernecking," Ms Graham says.

Roads in Canterbury are also flooded, including State Highway 1 at the Selwyn River bridge and Dunsandel. Parts of Christchurch are also flooded after the Heathcote River burst its banks.

Water levels were expected to peak for around an hour after high tide of the Heathcote River at 3.15pm.

Residents in low-lying areas in Lake Ellesmere are warned to move all stock; and if they feel anxious or unsafe they are advised to evacuated. The lake is expected to continue rising.

Meanwhile, more than a month of rain fell in Oamaru yesterday. Niwa climate scientist Nava Fedaeff said the average rainfall in Oamaru in July is 40.6mm. Between 6am and 5pm on Friday, 63.6mm of rain had fallen.

ROADS

A large number of roads are closed. For latest information check here.

Road Snowfall Warnings

• Lewis Pass (SH7) - Snow expected for a time during Saturday morning, with 2 to 4cm may settle near the top of the pass.
• Arthur's Pass (SH73) - Rain may turn to snow near the summit from tonight until early Saturday morning, with 2 to 4cm possible.
• Lindis Pass (SH8) - Snow expected near the top of the pass, with 5 to 10cm may accumulate there through to Saturday morning.
• Dunedin to Waitati Highway (SH1) - Rain may turn to snow or sleet near the summit for a time Saturday morning but little if any is expected to settle on the road.

Canterbury

• SH75 Halswell to Little River - Flooding - ROAD CLOSED
• SH1 Rolleston to Rakaia - Flooding - Follow directions of emergency services on site - ROAD CLOSED
• SH1 Rakaia to Ashburton - Flooding- road is now OPEN. Road users are advised to avoid unnecessary travel and to take extra care.
• SH1 Ashburton to Washdyke - Flooding - Road users are advised to avoid unnecessary travel and to take extra care.
• SH82 Waimate to Kurow - Flooding - OPEN
• SH79 Fairlie to Geraldine - Flooding - road is now open to one lane in sections
• SH77 Ashburton to Methven - Flooding - NOW OPEN
• SH N/A Route 70 Waiau to Kaikoura - ROAD CLOSED. Due to multiple slips and rockfalls, Inland Route 70 is now closed. Access to Mt Lyford is still available via Waiau.

Otago

• SH87 Kyeburn to Kokonga - Flooding - ROAD CLOSED
• SH87 Kokonga to Outram - Flooding - Road is OPEN - Road users are advised to take extra care.
• SH85 Palmerston to Kyeburn - Snow - Road CLOSED
• SH8 Roxburgh to Raes Junction - Flooding - ROAD is OPEN
• SH1 Oamaru to Waikouaiti - ROAD is now OPEN - surface flooding
• SH90 Waikoikoi to Tapanui - Flooding - ROAD CLOSED
• SH 1 Pukeuri To Waitaki Bridge - Flooding - ROAD CLOSED
• SH1 Balclutha to Milton - Flooding - ROAD CLOSED
• SH 83 Pukeuri To Omarama - Road is OPEN - surface flooding
• SH8 Raes Junction to Milton - Flooding - ROAD CLOSED
• SH88 Maia to Sawyers Bay - Flooding - ROAD CLOSED
• SH 1 East Taieri To Clarksville - Flooding
• SH 87 Mosgiel To Outram - Surface Water - Road users are advised to take extra care.
• SH 1 Waikouaiti To Waitati - Surface Water - Road users are advised to take extra care.
• SH 8 Raes Junction To Alexandra - Flooding

In Dunedin, progress is being made on clearing slips on Portobello Rd. Portobello Rd is expected to be open all the way to Tidewater Drive, Harwood to residents only from 5.30pm. However, please be aware that there is still surface water and debris on many parts of the road.

A slip on Harington Point Rd just past the turnoff to Harwood is still moving and clearance work on this will not start until at least Monday. This means that residents on the Otago Peninsula north of Harwood are effectively cut off, with no alternative access route available.

In Wellington, the Esplanade was closed briefly by a small slip. There were concerns that more rocks and soil would come down, but the road is now re-opened.

North of Auckland, a slip blocked part of State Highway 1 earlier today and has since been cleared.

Oamaru siblings Thompson (16) and Aynsley Martin (18) take advantage of a flooded Awamoa Park and skim board on the football field.
Oamaru siblings Thompson (16) and Aynsley Martin (18) take advantage of a flooded Awamoa Park and skim board on the football field.

POWER

Power has been lost to a number of areas overnight due to implications of the current weather.

Around 60 houses remain without power - most of them in Leith Valley and Henley. There is currently no estimated time for restoring power to properties in Leith Valley due to slips blocking road access.

Earlier, Aurora Energywas working restore power as soon as possible to areas including Old Brighton Rd, Green Island Bush Rd, St Leonards Dr and Berwick, Dunedin.

At this stage they are unable to provide a time of when power will be restored but will provide updates as information becomes available. Power could be restored at any time so please treat all electrical equipment as live at all times.