All Wellington train services have now been suspended until further notice as the region struggles to cope with the floods.
Wellington Railway Station is closed.
Earlier police rescued a cyclist caught by floodwaters in the Waikanae River.
The man was able to call for help on his mobile and was rescued with a digger.
Newstalk ZB's Tim Fookes says the message isn't getting through that people should stay away from flooded rivers and streams.
"Apparently the man was able to call for help on his mobile phone. He had to be rescued and police are on alert and trying to put out warnings to avoid being on the roads, especially flooded roads."
Palmerston North residents may be stranded in Wellington for the night.
The Capital Connection train, which runs between Palmerston North and the capital, is cancelled, and there are no buses to replace the service.
Earlier, evacuations started on the flood-hit Kapiti Coast.
Kapiti's emergency management centre has been activated.
The Kapiti Coast, Porirua and Hutt Valley are all now dealing with serious flooding events, and the district is struggling to cope after an absolute drenching this morning - roads and schools are closed, slips have blocked the Kapiti train line, and neighbourhoods are flooded.
Flooding is reported from Paekakariki to Otaki.
A Facebook page has been set-up to help those stuck in Wellington due to the floods.
Wellington City Council's Richard Maclean says people are leaving their homes in Tawa as the water levels rise.
He says people are also using sandbags to try and keep the water out.
The Waikanae River is rising, and the council says all parks and reserves in the area are closed. Hutt City council is advising anyone with cars in the riverbank carpark to move them.
Residents worried about rising waters are advised to move valuables to a safe place, and to stay out of the water as it could be contaminated with sewerage.
The Fire Service is being inundated with calls, as Kapiti residents awake to flooding in their homes.
Wellington Free Ambulance is activating back up plans.
Head of operations Rob Ives says flooding is affecting access in and out of the area, and the service is working with St John to make sure people can be reached.
He says extra ambulances are coming into the region, in case someone needs to be taken to Palmerston North Hospital for treatment.
Mr Ives says anyone needing urgent medical care should call 111, but if it's not an emergency, to use Healthline - 0800 611 116.
Road closures and travel delays
Travel wise - trains and their replacement buses are suspended between Plimmerton and Waikanae, and the main road connecting the Coast to Wellington is closed.
Valley Road, Emerald Glen Road and Waterfall Road in Paraparaumu are also closed due to debris.Water is up to car doors and rivers flowing across State Highway One.
Kapiti Coast residents heading for work this morning spent a long time going nowhere.
A severe weather warning for heavy rain has been issued for the Kapiti Coast, where nearly 60 millimetres has already fallen.
A slip's blocking State Highway One near Pukerua Bay, and it's also halted trains.
The Paekakariki Hill Road is also closed.
There's no detour as the Paekakariki Hill Road is also closed due to slips and flooding.
Train services on the Kapiti and Johnsonville lines are suspended.
NZTA's Mike Seabourn says the slip is blocking both lanes at the moment.
"We're trying to get one lane open by taking the material from one lane and putting it in to the other. It does mean however, for the whole day that we'll have a one lane open once we get it done."
Kapiti Coast Council is asking people to stay at home and wait for updates.
If you are on the road - here's some advice from NZTA spokesman Anthony Frith:
"We've had a real dumping of rain over the last few days and we really want to urge motorists to watch their following distances, drop your speeds lower than what they normally would be and just take a lot of care out there."
Mayor Ross Church says the council is keeping an eye on walk bridges over the Waikanae River.
"They don't want children going over those when the river is coming up and they're getting slippery. They're doing all they can to keep people safe at this stage."
Locals vouch for advice to stay off roads
Kapiti Coast Mayor Ross Church reiterates the message to stay home. After travelling though Otaihanga roundabout this morning he has told Newstalk ZB police are turning people around at the , but he was allowed through to Paraparaumu.
"I was glad I've got a big four wheel drive SUV because some of the surface road flooding was quite deep, and cars were really struggling to get through it."
Waikanae resident Keith Deverall has just arrived home after spending a nightmare hour and a half on the road.
"Water up to a metre deep on the side of the road around Paraparaumu so we've all given up and come home. I see there were some diggers on their way coming in towards Wellington."
Lightning rumours false
The Wellington Girls' College principal says the school hasn't been struck by lightning, as some reports suggest.
Julia Davidson says the school isn't closed.
She says there was a fire alarm, and girls were sent home as they were drenched.
The outlook ahead
Wellington is also set to get downpours, and gale force winds.
MetService forecaster Emma Blades says the rain's expected to ease this afternoon, but won't go away.
"There will be another period of rain developing again tomorrow morning, again with some possible heavy, thundery falls, and then some showers on Staurday."
Blades says Paraparaumu is bearing the brunt of most of the rain.
"Heavy falls are expected there through to this evening. There's also in addition to that a severe weather watch in place for possible heavy rain in Wellington and some North West gales."
- Photos via Twitter, Newstalk ZB Staff, Aisling James, Peter Ward, and NZTA