The agency, known as NRW, said the forecasts worry it and that flood response teams see a heightened risk over the coming months. After a summer of drought and wildfires, it urged people "not to become complacent" and warned that conditions can change quickly.
Floods have followed powerful storms in recent years, including Dennis in 2020, Bert and Darragh in 2024, and Claudia in 2025. They come from rivers and the sea, and surface water flooding, when heavy downpours overwhelm local drainage, is a growing danger. NRW says Wales is especially vulnerable because of its vast coastline and fast-responding rivers, which fill at speed as rain runs off steep terrain like the south Wales valleys.
NRW classes more than 274,500 homes and businesses, one in seven properties in Wales, as at risk. It expects that number to rise significantly by the end of the century.
In Monmouth, where major flooding hit in November 2025, people described "harrowing" and "dreadful" scenes. Friends Malcolm Butcher, 82, Jim Tyler, 81, Brian Churches, 82, and Dave Blake, 82, have lived in the town all their lives and "never seen anything like it." Malcolm said the water arrived at 2:30 in the morning. Had it come in daytime, he said, "people would have died." Residents in flood-hit areas told BBC Wales they are worried and have started preparing.
Only 27% of the people eligible for flood warnings by phone or email have signed up.