PHOTOS: Big wet causes flash flooding

PARTS of the Northern Rivers have copped almost 400mm of rain, and there's more coming on Monday and Tuesday.

SES crews have been out helping locals get prepared for the wild weather.

The Bureau of Meteorology has this morning issued a fresh severe weather warning for the Northern Rivers, with heavy rainfall, damaging winds, abnormally high tides and damaging surf expected.

Rainfall rates could be locally enhanced with thunderstorms, leading to the possibility of very heavy rainfall and dangerous flash flooding.