The Met Office has brought forward a yellow weather warning issued for south Wales due to heavy rain and potential flooding.

The weather warning was initially set to be in place from 5pm on Thursday (September 26) until 10am on Friday (September 27).

However, The Met Office announced on Thursday morning it had been brought forward and would now be in place from 6am on Thursday until 9am on Friday.

The heavy rain associated with the yellow weather warning is set to cause flooding, power outages, travel disruptions and potential danger to life.

The weather warning will affect all of South Wales including Newport, Blaenau Gwent, Monmouthshire, Caerphilly, Cardiff and Vale of Glamorgan. 

An amber weather warning has also been issued by the Met Office, affecting areas just over the south Wales border to the east.

This amber warning will be in place from 6pm on Thursday until 6am on Friday.

What to expect from the yellow weather warning in South Wales

The Met Office said the yellow weather warning was issued across South Wales due to heavy rain which could result in flooding and disruptions to transport.

The heavy rain associated with the yellow weather warning is also set to cause:

  • Power cuts and disruptions to other services
  • Homes and businesses could be flooded, causing damage to some buildings
  • Delays or cancellations to train and bus services where flooding occurs
  • Difficult driving conditions and road closures due to spray and flooding
  • Communities becoming cut off by flooded roads
  • Fast flowing or deep floodwater causing danger to life

A Met Office spokesperson added: "Whilst some areas will miss the worst, heavy showers and some thunderstorms will occur during today, potentially becoming more organised across a swathe of Wales and into central and eastern England during Thursday evening and on into early Friday morning.

"10-15 mm of rain could occur within an hour from the heavy showers during today with a few places possibly seeing 30 mm over a few hours.

"There still remains some uncertainty in the details for Thursday evening and overnight, but some locations may see up 20-30 mm of rain in 2-3 hours and perhaps 40-60 mm in 3-6 hours.

"Given the recent very wet weather, this will bring the potential for further flooding and transport disruption.

What different Met Office weather warnings mean

Everywhere in Wales set to be affected by yellow weather warning

Areas of Wales set to be impacted by the yellow weather warning issued by the Met Office are:

  • Blaenau Gwent
  • Bridgend
  • Caerphilly
  • Cardiff
  • Carmarthenshire
  • Ceredigion
  • Merthyr Tydfil
  • Monmouthshire
  • Neath Port Talbot
  • Newport
  • Pembrokeshire
  • Powys
  • Rhondda Cynon Taf
  • Swansea
  • Torfaen
  • Vale of Glamorgan

A yellow weather warning has been issued for all of south Wales, while and amber weather warning has been issued for other parts of the UK just over the border.A yellow weather warning has been issued for all of South Wales, while an amber weather warning has been issued for other parts of the UK just over the border. (Image: Met Office)

How to prepare for the yellow weather warning in South Wales

The Met Office has issued advice on how to prepare for the yellow weather warning and the risks it poses.

A Met Office spokesperson said: "Check if your property could be at risk of flooding. If so, consider preparing a flood plan and an emergency flood kit.

"Give yourself the best chance of avoiding delays by checking road conditions if driving, or bus and train timetables, amending your travel plans if necessary.

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"People cope better with power cuts when they have prepared for them in advance. It’s easy to do; consider gathering torches and batteries, a mobile phone power pack and other essential items.

"Be prepared for weather warnings to change quickly: when a weather warning is issued, the Met Office recommends staying up to date with the weather forecast in your area."

The yellow weather warning will be in place across South Wales from 6am on Thursday (September 26) to 9am on Friday (September 27).