Rain is expected for much of the state from Tuesday, including fire grounds across the Snowy Mountains, southwest of Sydney and South Coast regions.

But the NSW Rural Fire Service warned that because much of the rain would come with thunderstorms, downfalls could be patchy and there was no guarantee they would extinguish the 105 fires burning across the state on Monday night.

The Bureau of Meteorology said it was difficult to predict exactly how much rain would fall because the downpours will be inconsistent.

Bega on the south coast was expected to receive between 3mm and 10mm on Thursday, when most rain is predicted to fall. However in Cooma, just 100km inland, greater falls of between 8mm and 25mm are forecast.

"We will have thunderstorms as well as showers," BOM meteorologist Elli Blandford said.

"The rainfall total could be patchy in some areas. It could be quite high due to thunderstorms and then down the road might not receive as much."

The RFS also warned that thunderstorms could create the risk of falling trees and landslips.

Fires have destroyed 2163 homes in NSW this bushfire season, with more than 1200 having burned down since New Year's Eve.

The NSW government was urging people with holiday homes in bushfire-affected areas to make them available to residents who lost their homes.

As part of the scheme to get people out of emergency accommodation, the state government will cover rental bond loans and advance rent payments.

"We have literally hundreds of displaced people, we need to get them longer-term accommodation, beyond the crisis accommodation which people are currently living in," NSW minister for transport and Bega MP Andrew Constance said.

"We've got people living in caravan parks, hotel rooms, with neighbours, with friends, in sheds. We've got to get people placed and one solution to that is freeing up many coast homes that won't necessarily have people in them."

Meanwhile the Blacktown City Council said it had cancelled its Australia Day fireworks out of respect for people who had lost their homes and the risk of them causing new fires.

Australian Associated Press