Two crews and a hovercraft from Weston-super-Mare were called just after midnight to rescue two adults and the children from Uphill beach.
The police and ambulance service also attended, the fire service said.
Avon Fire and Rescue have warned people not to park or walk on the beach in the dark due to the fast-rising tides.
A family of five, including three young children, had to be rescued from a Somerset beach after their car got stuck in the mud on Saturday evening.