Natural Resources Wales is asking people to remain vigilant as a band of persistent heavy rain and gale-force winds approach Wales again.
Up to 20 millimetres of rain is expected across South Wales with up to 40 millimetres (one-and-a-half inches) on higher ground from tonight into tomorrow morning.
With the ground saturated after periods of heavy rain before Christmas, this further rainfall will quickly find its way into rivers and streams.
There is also an ongoing risk that leaves and other debris brought down by strong winds could block drains and cause roads to flood.
People travelling after the Christmas break are advised to allow extra time as driving conditions may be difficult.
Natural Resources Wales is also asking people to take care near fast-flowing and swollen rivers and along the coast where strong winds could cause large waves.
It advises people to keep an eye on local news and weather forecasts for news of any disruption in their area, and warns of the dangers of walking or driving through flood water.
Officers from Natural Resources Wales will be monitoring forecasts closely during this time and will issue flood alerts and flood warnings when required.
Teams continue to check that flood defences are in good working order and that rivers are clear of debris which could restrict river flows.
Flood warnings are updated every 15 minutes at www.naturalresourceswales.gov.uk/alerts
People can also follow the latest updates on Twitter @natreswales