Climate change is going to bring four times the amount of hot days in Wellington and Wairarapa in the next 100 years and there's also likely to be more frequent extreme rainfall events, a NIWA report says.

Photo: RNZ

A number of projections for how the warming climate will affect the lower North Island have come out as part of a report commissioned by the Wellington regional council.

The NIWA report said Wairarapa was likely to go from 24 to 94 days with temperatures above 25° while Wellington will increase from six to 26 days.

There was likely to be an increase of droughts in Wairarapa with a 10 percent drop in rainfall but in Wellington, there's likely to be an increase of rain in all seasons and up to 15 percent more in winter.

NIWA chief scientist for climate, atmosphere and hazards Sam Dean said the New Zealand landscape had gone through a lot of changes because of greenhouse gas emissions.

"We already live in a country that climate-wise is dramatically different from those that the tangata whenua and the early European settlers experienced when they first arrived here.

"This is because of human emissions of greenhouse gases as well as ozone-depleting substances."

Dr Dean said NIWA began working on the report about a year ago and it was led by climate scientist Petra Pearch, who gathered information from work done by the Intergovernmental Panel on Climate Change (IPCC).

"This particular report gives high-resolution information about the Wellington region. It zooms in on the Wellington region and makes the information available in a way that allows people who live here to understand what the possible implications of climate change are for this region."

The report was based on calculations from a super-computer based at NIWA's Greta Point office.

"Just running the simulations that produce the projections alone took about two years on that computer.

"It involved the development of a lot of world-leading techniques to produce the information of the kind of resolution that's available in this report."

Photo: Supplied

Greater Wellington Regional Council chair Chris Laidlaw said due to a lack of direction from central government, it was time for local councils to take a lead on planning for climate change.

"There is a huge groundswell around this country, demanding action.

"I get letters from people saying 'why are you not doing more than you're doing'. Part of the problem has been something of a disconnect between government and local government."

Mr Laidlaw said there was a plethora of climate change impacts the council needed better planning for.

"Sea incursions, the battering that our coasts are going to take from bigger and more intensive storms.

"How we deal with flood protection around the region. Are we doing enough? Are we doing the right thing? Should we be looking at alternative approaches like managed retreat?

"Questions like those are really top of mind for us as we move forward on climate change."