A huge area of St Asaph, in Denbighshire was flooded after the River Elwy burst its banks yesterday morning.
Hundreds of people had to be evacuated from their homes as flood water continued to rise.
North Wales Police says 500 homes were evacuated, and more than 100 found shelter in a leisure centre in the city, receiving hot drinks and blankets, with help from the British Red Cross.
According to our reporter, Ian Lang, who was in St Asaph yesterday, the flood water was waist deep in some places, engulfing cars and trapping people in their homes.
A Rest Centre remained open overnight for those rescued from the flood. North Wales Police and other emergency services also worked throughout the night.