UPDATE 3.55pm: There are reports hail has fallen at Tregeagle this afternoon.

UPDATE 3.40pm: The Bureau of Meteorology has increased its severe thunderstorm warning to include all of the Northern Rivers.

BoM said thunderstorms were likely to produce damaging winds, large hailstones and heavy rainfall that may lead to flash flooding in the warning area over the next several hours.

Locations which may be affected include Lismore, Grafton, Tenterfield, Kyogle, Yamba and Maclean.


UPDATE 2.40pm: Severe thunderstorms are likely to produce large hailstones and heavy rainfall that may lead to flash flooding on the Northern Rivers this afternoon.

BoM said the locations which may be affected include Tenterfield, Casino, Kyogle, Tabulam, Nymboida and Ebor.

The State Emergency Service advises that people should:
* Move your car under cover.
* 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.


Original story: Thunderstorms could develop on the Northern Rivers today, and could be severe, the Bureau of Meteorology warned.

BoM meteorologist Helen Reid said remnants of a trough continued to impact the region and widespread rainfall could be expected as well as possible thunderstorms.

<<< Why are thunderbolts and lightning very, very frightening? >>>

She said it was hard to predict where the rain would fall, but some areas could receive up to 40mm.

Ms Reid said the impact of La Nina was beginning to weaken, but we could still look forward to slightly higher than average rainfall for the autumn months.

Watch BoM report here.