Parts of north-western NSW could spend more than a third of the year above 35 degrees Celsius by 2070, according to new projections released by the NSW Government.

The projections map out for the first time how different parts of New South Wales could be affected by climate change in the near and distant future.

The detailed modelling, produced through a partnership with the NSW and ACT governments and the University of NSW Climate Change Research Centre, suggested that by 2070 average temperatures in the state will have risen by 2.1 degrees.

Summer and spring will see the largest change with maximum temperatures up to 3 degrees higher.

The Office of Environment and Heritage's director of climate and atmospheric science, Matt Riley, said north-west New South Wales would notice the difference with up to 40 extra days each year reaching 35 degrees by 2070 in areas like Bourke and Moree.

"So that means that by 2070 it's likely that more than a third of the year in north-western NSW will be above 35 degrees," he said.

Other regions where changes in temperature could wreak havoc include the Snowy Mountains, with up to 40 fewer nights expected to have temperatures below 2 degrees.

The modelling suggests the impact will already be felt by 2030, with 20 fewer cold, snow-producing nights in the area.

"That will obviously have an impact on ecosystems that rely on cold weather, agriculture that relies on cold weather - for example for buds to form or fruiting to commence - but also snow tourism as well," Mr Riley said.

While the amount of rain expected overall across the state is predicted to remain fairly stable - the modelling suggests there will be more rain in autumn and less in spring.

Mr Riley said that sort of information could be used by the Department of Primary Industries, farmers and local communities in planning crops and water infrastructure.

Other changes predicted by the modelling include:

Spring rainfall in southern NSW and the Riverina will decrease by more than 10 per cent by 2070

Spring rainfall in southern NSW and the Riverina will decrease by more than 10 per cent by 2070 The greatest increases in severe fire weather will occur west of the Great Dividing Range during spring

The greatest increases in severe fire weather will occur west of the Great Dividing Range during spring Increases in severe weather days during spring may increase bushfire risk and reduce opportunities for hazard reduction burning.

NSW Environment Minister Rob Stokes said it was world-leading research that would help state and local authorities plan for the future.

"I think some of the takeaways that some of the agencies will be interested in will obviously be in relation to water security and future planning around water infrastructure," he said.

"Also extreme temperatures and what that means in relation to health the consequences of extreme heatwaves, for example, and also particularly the ever-present threat of bushfire."

Viticulture consultant Liz Riley examines a vineyard in the Hunter Valley that could be affected by climate change. ( Supplied: Peter Robey )

Increases in severe fire weather were predicted in Canberra for both summer and spring, ACT's Environment Minister said.

"The implications mean it will be much harder to manage fire, it will be much harder to undertake hazard reduction burns because spring will be too hot," Simon Corbell said.

"The analysis tells us that we will see up to an extra 20 days above the 35-degree [Celsius] mark by the year 2070.

"It's worth remembering that this will occur within the lifetime of young man who is now 15 years old, this is not some far distant future."

The NSW Government spent about $2.8 million on the project and Mr Stokes said it was a sound investment.

"If it can help people make wise decisions to make infrastructure and investments resilient to future change, then ultimately we believe that this investment up front can save hundreds and hundreds of millions into the future," he said.

The information is publicly available on the Office of Environment and Heritages website.