The study revealed NSW can expect fewer frosts but more frequent droughts, heatwaves, rainstorms and strong winds.

It considered a number of climate change scenarios, including drought, extreme daily temperatures, extreme rainfall and extreme winds.

The study found the number of days per year over 40 degrees around Walgett may double or even triple by 2030.

The cause of the changes in the weather has been attributed to the increase in greenhouse effect.

The study's best-case scenario predictions, based on low levels of global warming included most places having between 5 to 20 per cent more days per year above 35 degrees by 2030 and 20 to 60 per cent more by 2070; and Inland NSW may have 10 to 20 per cent fewer frosts per year by 2030 and 30 to 50 per cent less by 2070.

Under the worst-case scenario, based on high levels of global warming most places may have between 50 to 100 per cent more days per year above 35 degrees by 2030 and 100 to 600 per cent more by 2070; the frequency of frost days may at least halve by 2030, with some places becoming frost free; and by 2070 cold spells would be extremely rare.

There is also a tendency for mean wind speed and extreme winds to increase in spring, with the greatest increases across central NSW.

While much of NSW shows a tendency for drier season al-average conditions under enhanced greenhouse conditions, heavy rainstorms may become more frequent.

The study shows this to be most likely in central and south-east NSW and the far northeast, particularly in summer.

In autumn and winter, heavy rainstorms are likely to increase in the centre and northwest of the State, and decrease on the coast.