UPDATE: The Severe Thunderstorm Warning has been cancelled at 10:48am.

The Bureau of Meteorology has issued a Severe Thunderstorm Warning for heavy, locally intense rainfall for Lismore and the Northern Rivers.

Slow-moving thunderstorms triggered by a southerly change moving up the coast are resulting in heavy rainfall for parts of the Northern Rivers district.

Severe thunderstorms are likely to produce heavy, locally intense rainfall that may lead to dangerous and life-threatening flash flooding in the warning area over the next several hours. Locations that may be affected include Lismore, Mullumbimby, Alstonville and Nimbin.

43 mm of rainfall was recorded at Lismore (Dawson Street) in the 30 minutes to 9:15 am.

There are reports of flash flooding so remember, don't drive through flooded water.

The State Emergency Service advises that people should:

* 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.

* Be aware that run-off from rainfall in fire affected areas may behave differently and be more rapid. It may also contain debris such as ash, soil, trees and rocks.

* After bushfires, heavy rain and the loss of foliage can make the ground soft and heavy, leading to a greater chance of landslides.

* 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.

The next warning is due to be issued by 12:35 pm.