Dubbo received more than 25mm in the 24 hours to 9am Monday with a forecast of 100 per cent chance of rain throughout the day and a severe weather warning for heavy rainfall is in place for the central west slopes and plains and multiple other districts.

But in other parts of the state a huge weather event caused devastating flash flooding, with roads and highways still closed or impacted early on Monday morning.

The Great Western Highway was added to the list of routes impacted just before 7am on Monday as a fallen tree was impacting eastbound traffic at Medlow Bath, just beyond Blackheath.

Drivers travelling along that road were advised to exercise caution and avoid the area along with allowing extra time with water pooling near Springwood and adverse weather warnings through Katoomba as well.

The updates came as the Bells Line of Road at Mount Tomah remained closed due to a severe landslide, as of 6.45am on Monday.

Further down Bells Line of Road the North Richmond Bridge between Pitt Lane and Chapel Street also remained closed due to flooding.

Motorists are advised to avoid the area.

For motorists heading between Dubbo and Newcastle, the Golden Highway remains closed in both directions between Range Road and New England Highway through the Singleton Military Area.

Diversions are via Putty Road and the New England Highway, the Transport Management Centre reports.

Bathurst's State Emergency Service unit also advised, at about 7am, they were preparing to close the low level bridge on Hereford Street as the Macquarie River had risen to the point of flowing over the crossing.

South of Bathurst, Oberon Council has advised that the low-level Abercrombie Road bridge across the Abercrombie River is under water with motorists being turned around either side of the bridge.

Elsewhere, the Jenolan Caves Road between the Great Western Highway and Edith Road was closed in both directions with drivers to take an alternate along the Great Western Highway to Bathurst and then O'Connell Road to Oberon.

That road is expected to be closed for several days.

Further along Jenolan Caves Road, the Five Mile between Duckmaloi Road intersection and the Grand Arch, and the Two Mile Road between the Grand Arch and Kanangra Walls Road remain closed.

The Jenolan Caves precinct was closed to the public on Friday and is not expected to reopen before Tuesday.

If you must still travel, please stay informed via Live Traffic and drive to the conditions.

Late on Sunday night emergency services responded to a fallen tree on the Mitchell Highway near Wongarbon that closed the highway, NSW Rural Fire Service Eulomogo said in a post to Facebook.

Volunteers from the RFS brigades removed the tree and debris, allowing the highway to reopen.

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