Slow-moving thunderstorms delivered the heaviest rain in two years to parts of northeast NSW during the last 24 hours.

A coastal trough moving over land caused heavy rain and storms in the state's northeast during Thursday night and Friday morning.

Lismore Airport received 63mm of rain between 5:30pm on Thursday and 9am Friday, which was its highest daily total since October last year.

Further north, a rain gauge at Doon Doon registered 170mm during the 24 hours to 9am on Friday, which was its heaviest rain in two years.

Thunderstorms also brought 10-30mm of rain to parts of the Northern Tablelands and North West Slopes and Plains districts on Thursday afternoon and evening.

Inverell creceived 32mm during one intense storm just before 4pm on Thursday, with 18mm falling in just 10 minutes.

Showers and thunderstorms will develop over the northern inland of NSW again on Friday afternoon. Visit http://www.weatherzone.com.au/warnings.jsp for the latest warnings.