The bulk of that rain, weatherzone.com is predicting, should fall over Thursday and Friday, with a 90 per cent chance of rain on both days.

As much as 10mm is on the radar for Thursday, while Friday is expected to be very wet - there's as much as 20mm forecast for Orange to end the working week.

While more showers are expected over the weekend and then again to kick off the following week on Monday, it's the initial downpours that have a lot of the low-lying regions across Orange ready for more rising waterways.

The second crossing at Ophir flooded last week after around 60mm of rain in less than 24 hours, while southern parts of NSW were absolutely smashed and huge flooding was recorded along the banks of the Murrumbidgee River.

Just after lunchtime on August 11, the Bureau of Meteorology has placed the inland rivers in NSW on flood watch.

The warning said flooding is possible for inland rivers from Friday morning.

It says a cold front associated with a low pressure system is expected to bring showers and rain to western New South Wales from late Thursday, extending to eastern parts of the state during Friday.

"This rainfall may cause widespread minor to moderate and possibly major flooding along inland NSW rivers, many of which experienced flooding due the rainfall last week," the bureau said.

Catchments are wet following recent rainfall. So far in August we've had 65mm of rain. The average for the eighth month of the year in Orange is just shy of 94mm.

"The weather system is expected to cause renewed flooding for the following catchments listed from Friday," the warning added.

Flood Warnings are current for the following catchments: Namoi, Macquarie, Bogan, Lachlan, Murrumbidgee, Murray, Mirrool Creek, Culgoa, Narran and Darling.

For the latest flood and weather warnings see www.bom.gov.au/nsw/warnings/

For the latest rainfall and weather forecasts see www.bom.gov.au/australia/meteye/

For the latest rainfall and river level information see www.bom.gov.au/nsw/flood

This Flood Watch means that people living or working along rivers and streams must monitor the latest weather forecasts and warnings and be ready to move to higher ground should flooding develop.

Flood Warnings will be issued if Minor Flood Level is expected to be exceeded at key sites along the main rivers for which the Bureau of Meteorology provides a flood warning service.

Severe Weather Warnings will be issued or updated if very heavy rain is forecast or observed.

For more information on the Flood Watch Service: http://www.bom.gov.au/water/floods/floodWarningServices.shtml

FloodSafe advice is available at www.ses.nsw.gov.au

For emergency assistance call the SES on telephone number 132 500. For life threatening emergencies, call 000 immediately.