Storm Bert floods more than 700 homes in Wales

Storm Bert brought very wet and windy weather to Wales from 22 to 25 November 2024, and more than 700 homes across Wales experienced flooding, according to Natural Resources Wales (NRW)¹. Pontypridd, which was badly affected during Storm Dennis in 2020, was again one of the most severely affected communities¹.

NRW reports widespread rainfall totals of 50 to 100mm across Wales, with over 150mm in the wettest upland areas¹. In many places in South Wales, rainfall over the three days from 22 to 24 November was 70% or above of the November average, and 23 November was the wettest day in the UK since October 2020 and the 12th wettest in the UK series from 1891¹. On already wet catchments, this led to some rivers in South Wales reaching their highest ever recorded levels¹.

A landslip occurred at Cwmtillery in Blaenau Gwent, where a disused coal tip partially collapsed, forcing the evacuation of around 40 homes because of rock and mud flowing onto residential streets¹. A large sinkhole opened on a residential street in Merthyr Tydfil after an underground culvert was damaged by boulders¹. Flooding and infrastructure damage disrupted railways, including closure of the Heart of Wales and Marches lines, and many roads closed, including the A479 in Powys and the A4042 in Monmouthshire¹.

Storm Darragh followed on 6 and 7 December 2024, two weeks after Bert, bringing very strong winds to West Wales and the South Wales coast and a rare red weather warning from the Met Office¹. The UK Government issued an emergency alert by phone to affected areas, the first use of the system since it was introduced in 2023¹. NRW reports that destructive winds significantly damaged power infrastructure, with more than 259,000 homes without power at the peak of disruption¹.

Why it matters for households

NRW estimates there are 275,000 properties at risk of flooding in Wales, approximately 1 in 7¹. As of April 2025, the undefended sum of properties at risk is 342,436, and removing double or triple counting of properties at risk from multiple sources leaves over 274,000¹. NRW predicts that by 2120 there will be over 131,000 properties at risk from the sea and nearly 131,000 from rivers, increases of nearly 40,000 and over 24,000 respectively from the present day, with over 48,000 more at risk from surface water and small streams².

On warnings, NRW's new Flood Warning Information Service for Wales went live on 17 July 2024, a £5m multi-year project that replaced the previous system and decouples Wales from the previous England and Wales service¹. November was the month with the most visits to the NRW website, with nearly 400,000 total visits resulting from Storm Bert¹. The British Red Cross, in a UK-wide survey of over 3,300 people, reports that only 1 in 6 adults are signed up to receive flood warnings, and that only half of those flooded in the last 5 years say they have seen information about flooding⁴. Of those who had been flooded, 40% reported moderate to severe mental health impacts and 42% reported moderate to severe impact to their finances⁴.

What happens next

The Welsh Government published a revised planning policy, TAN15: Development, Flooding and Coastal Erosion, on 31st March 2025¹. NRW released an updated Communities at Risk Register in January 2025, alongside a Climate Change CaRR for the first time¹. Its project to replace the ageing Telemetry system is due for roll out later in 2025¹. NRW reports investment of £47m of Welsh Government funding on key flood risk management activities in 2024/25, and completion of the Stephenson Street flood alleviation scheme in Newport, reducing flood risk to 1,032 properties¹.

Households can read the flooding guide, check Natural Resources Wales warnings and risk maps for Wales, and understand flood alerts, flood warnings and severe flood warnings. Guidance is also available on flood defences and alleviation schemes, flood doors and flood windows, and home insurance in a flood risk area and Flood Re.