Bushfire-ravaged communities are preparing ahead of forecast heavy rainfalls that authorities fear could cause slips and flooding in some parts of NSW.

Rainfall totals of 30 to 80 millimetres are forecast from Thursday, with strong falls possible for fire grounds in the Snowy Mountains, southwest of Sydney and South Coast regions.

The Bega Valley Shire Council said it would work with the RFS to manage any impacts caused by the deluge.

“Weather predictions indicate conditions are favourable over the next week for the containment effort,” the council posted on its Facebook page.

“There is predicted rainfall from Thursday onwards – early indications show the possibility of heavy rainfall which may impact on sediment runoff into waterways.

“This situation is being monitored and planned for by council and RFS.”

Firefighters have welcomed the forecast as the best news in months but the Bureau of Meteorology said the rain could be a “double-edged sword”.


“Hopefully some of this heavy rainfall will fall over fire sites and help control or even extinguish fires,” meteorologist Sarah Scully said on Tuesday.

“But it’s a bit of a double-edged sword because heavy rainfall and gusty thunderstorms bring the potential for flash flooding, particularly in the burnt-out areas of NSW and Victoria which are now vulnerable to land slips and trees coming down.”

Mr Fitzsimmons said filtration and other equipment is being deployed into the water systems to protect drinking supplies.

NSW Water Minister Melinda Pavey said the government was using silt curtains to stop ash being washed into Warragamba Dam by heavy rainfall.

The fire service has been working closely with the SES, NSW Police and the Bureau of Meteorology to track the location of the heaviest falls.

Despite the easing conditions, fire danger ratings are still high for large parts of NSW on Wednesday.