The Bureau of Meteorology has issues a severe weather warning which includes Lismore, Casino and Coraki.

A convergence trough about northeast New South Wales is leading to severe thunderstorms.

Severe thunderstorms are likely to produce large hailstones in the warning area over the next several hours. Locations which may be affected include Lismore, Casino, Coraki, Rappville and Woodburn.

The State Emergency Service advises that people should:

* Move your car under cover.

* Unplug computers and appliances.

* Avoid using the phone during the storm.

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

* Stay vigilant and monitor conditions. Note that the landscape may have changed following bushfires.

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