Households in the UK are being urged to stock up on first aid supplies on Monday (December 1) with heavy rain forecast to lash some areas. The Met Office has issued a rare 24-hour “danger to life” amber warning for rain, with residents warned of potential flooding and power cuts.

The warning, which is in place from 12am until 11.59pm on Monday, covers a large part of Wales, including Blaenau Gwent, Bridgend, Caerphilly, Cardiff, Carmarthenshire, Merthyr Tydfil, Monmouthshire, Neath Port Talbot, Newport, Pembrokeshire, Powys, Rhondda Cynon Taf, Swansea, Torfaen, Vale of Glamorgan. The Met Office states: “Heavy rain is likely to bring some disruption and probable flooding on Monday.”

The forecaster is also urging people to prepare a flood kit to “save from loss or damage” caused by flooding. They explain that the flood kit should include a “first aid kit, prescription medicines and supplies for looking after your family members or pets”.

They also advise: “Consider checking on vulnerable people that you know, including older people, those with underlying conditions and those who live alone; they may need support with food and medical supplies. If you are worried about your health or that of somebody you know, ring NHS 111.”

Heavy and persistent rainfall is forecast to hit the south Wales region on Monday. Areas of higher ground, including Bannau Brycheiniog, are expected to see the heaviest downpours.

According to the Met Office, between 20mm and 40mm of rain is likely to fall across the region. However, between 60mm and 80mm could fall over some windward-facing high ground in south Wales and perhaps nearer 100-120 mm in a few places.

They said: “An area of heavy rain is expected to move over south Wales between late Sunday and late Monday. Whilst rainfall amounts will vary, some heavy and persistent rainfall is likely to fall, especially over high ground, for example Bannau Brycheiniog. Rain should clear to the east Monday night.”

Local people are advised to avoid travelling by road if the conditions are dangerous. If they do travel, they are urged to be cautious and watch out for standing water.

The forecaster added: “It is not safe to drive, walk or swim through floodwater, avoid it where possible and if you are affected by fast flowing or deep-water call 999, and wait for help.”

The Met Office has also outlined what to expect during the amber rain warning: 

• Homes and businesses could be flooded, causing damage to some buildings
• Delays or cancellations to train and bus services are possible
• Spray and flooding could lead to difficult driving conditions and some road closures
• Possible power cuts and loss of other services to some homes and businesses
• Some communities may be cut off by flooded roads
• Fast flowing or deep floodwater is possible, which could cause a danger to life