Residents in towns located across northern NSW have been advised to brace for a wet weather on Thursday evening going towards Friday morning in what could also potentially result to floods, according to the Bureau of Meteorology (BoM).

The BoM on Thursday morning issued a severe weather warning for damaging winds and heavy rain for the northern rivers, mid-north coast and northern tablelands districts.

The tropical low pressure system could bring flash flooding to the affected areas as well as moderate to major river flooding, according to the BoM. For this, it issued a flood watch for a huge swathe of NSW, stretching from the Queensland border to the Hunter Valley north of Sydney, as it warned some areas could expect rainfall of more than 300mm over Thursday and Friday.

From Thursday night to Friday morning:

1. Tweed River valley - minor to moderate flooding

2. Brunswick River valley - moderate flooding

3. Richmond and Wilsons River valley - moderate to major flooding

From Friday morning:

4. Clarence River valley - moderate to major flooding

5. Coffs Harbor - moderate flooding

6. Bellinger and Nambucca River valleys - major flooding

7. Macleay River valley - moderate to major flooding

8. Hastings River valley - moderate to major flooding

9. Camden Haven valley - minor to moderate flooding

From Friday night:

10. Manning River valley - minor to moderate flooding

11. Hunter River valley - minor to moderate flooding

"All the catchments are completely saturated so the rainfall that we get from this event will largely be run-off and the rivers will rise very fast, so widespread rain throughout the area may be fractionally less up towards the Queensland border, but there's still widespread floods across the area," Mick Logan, BoM senior forecaster, said.

He also added more rain and showers are predicted next week.

Residents in the affected areas have been advised to stay clear of any rivers, creeks or low-lying areas as these can be prone to flash flooding. Authorities from State Emergency Services likewise urged people to start preparing to go to higher land or areas within their respective properties.

"They need to start thinking about moving their cars and other valuables to higher land or higher areas within their property and they mostly need to be prepared to move if the SES start ordering evacuations or other response measures," Danny Rose, Tweed Shire Council planning and infrastructure engineer, said.