Destructive wind, hail and heavy rain set to lash northern New South Wales

A severe thunderstorm warning has been issued for the Northern Rivers, Mid North Coast and surrounding regions as damaging weather conditions approach this afternoon.

Flash-flooding may be triggered by the deluge of rain and large hailstones in the next several hours, the Bureau of Meteorology has warned.

Locations which may be affected include Lismore, Grafton, Coffs Harbour, Tenterfield, Sawtell and Dorrigo.

Port Macquarie, Kempsey, Armidale, Glen Innes, Inverell and Moree have also been issued with a warning.

The State Emergency Service (SES) has advised people in affected regions to:

* Move your car under cover or away from trees.

* Secure or put away loose items around your house, yard and balcony.

* Keep at least 8 metres away from fallen power lines or objects that may be energised, such as fences.

* Report fallen power lines to either Ausgrid on 131 388, or Endeavour Energy on 131 003 or Essential Energy on 132 080, as shown on your power bill.

* Keep clear of creeks and storm drains.

* Don't walk, ride your bike or drive through flood water.

* If you are trapped by flash flooding, seek refuge in the highest available place and ring 000 if you need rescue.

* Unplug computers and appliances.

* Avoid using the phone during the storm.

* Stay indoors away from windows, and keep children and pets indoors as well.

* For emergency help in floods and storms, ring the SES (NSW and ACT) on 132 500.