Auckland has been drenched with more than one-third of the normal annual rainfall already during 2018 - and we're only 43 days in.

A string of major weather events over the start of this year has made for a wet, but warm climate for the country - and with the potential landfall of Tropical Cyclone Gita early next week the big wet looks set to continue.

Niwa reported this afternoon the organisation's climate centre on Auckland's North Shore had recorded 434.6 mm of rain so far this year.

This equated to 36 per cent of the normal annual amount, in just 12 per cent of the year.

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A Metservice spokesman told Fairfax more rain had hit Auckland in the last 43 days than almost the entire last half of 2017.

MetService meteorologist Ravi Kandula said the Whangaparaoa region, just north of Auckland, had been hit with 169mm of rain so far this month.

This already tripled the monthly average of 53mm of rainfall and created a new record since Metservice began tracking rainfall in 1990.

The rainiest February on record prior to this was in 2001, when 136mm of rain hit the region.

Kandula said rainfall recorded at the other two stations in the Auckland region had been higher than usual in both January and February.

"Essentially if you're looking at averages it's unusual," he said.

"It's not something that we're seeing year on year ... otherwise our averages wouldn't be so low."

Auckland motorists braving a trip on Tamaki Dr before it was closed due to surface flooding last month. Photo / Greg Bowker
Auckland motorists braving a trip on Tamaki Dr before it was closed due to surface flooding last month. Photo / Greg Bowker

Kandula said the wet weather was set to continue overnight and into Wednesday.

"Tomorrow will see rain, sometimes heavy and likely some thunderstorms," Kandula said.

"This will ease overnight on Wednesday, with much better weather expected on Thursday."

Earlier today MetService lead meteorologist Michael Martens told the Herald a tropical trough hovering over the North Island was behind the "incredibly humid conditions".

Martens said this could cause fog, or 100 per cent humidity.

"That is unheard of. It is what you expect in the Cook Islands and the tropics."

Tropical Cyclone Gita is scheduled to pass south of New Caledonia on Saturday before travelling south into the Tasman Sea.

"Early next week there is a chance it may reach New Zealand, but the model is still uncertain," Martens said.

"Once it moves out of the tropics and the sea temperature decreases it will lose a lot of its power.