People trying to get in and out of Wellington can expect more delays today.

The first international departure flight for Brisbane was due to leave at 6am but has been delayed until 8.45am.

The first domestic flight to Auckland was set to depart at 6.15am but that's been delayed until just before 10am.

And the first flight set to land at the airport from Auckland has been cancelled.

However, an international flight to Sydney and two domestic flights to Auckland and Rotorua have taken off this morning.

All flights were suspended last night after heavy rain affected Wellington Airport's Instrument Landing System.

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About 50 passengers spent the night sleeping in the terminal.

Travellers are being advised to check the website for flight information.

Roads closed

This is compounded with several roads closed in the capital due to flooding.

One lane is now open in each direction at the Plimmerton Roundabout, but delays for traffic heading southbound are around 25 minutes.

Earlier the morning, the roundabout was completely underwater.

Gray's Road has also been closed because of flooding.

Evacuations

Wellington Region Emergency Management Office regional manager Bruce Pepperell​ said residents were evacuated from near the Owhiro Bay stream as a precaution.

About 50 people were evacuated from their homes last night near the stream and relocated to the Owhiro Bay School, but that was closed about 1am when all but a few of the evacuated people found accommodation with friends and family.

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The remaining people had accommodation organised for them.

"[They] were evacuated as a precautionary measure," Pepperell said. "Staff were going to have a look at first light as to what the situation is."

Overnight parts of Wellington experienced small slips, surface flooding, and a power pole was knocked down, briefly damaging a gas line.

"We've been monitoring the rivers in the Hutt Valley and Porirura, particularly over in the Wairarapa; river levels in the Wairarapa have been up.

"I think we got away reasonably lightly compared to up north."

More than 50 people who evacuated from their homes in Wellington are waiting to see when it will be safe to return this morning.

Just before midnight, 24 families were asked to leave their homes in the suburb of Owhiro after a nearby stream burst its banks.

The Wellington Region Emergency Management Office says it was mostly precautionary, but the damage to property will not be able to be assessed until later this morning.

The Wellington City Council has activated its welfare centre at Owhiro Bay School.

Overall, the fire service says it's been a fairly quiet night for it in Wellington.

Communications shift commander Murray Dunbar says it has dealt with fewer than a dozen weather-related call-outs.

He says they attended a landslip in Newtown last night but left when utility services arrived to fix a ruptured gas line.

-additional reporting Katrina Bennett, Newstalk ZB