The amber warning will be in place from 1am on Monday (June 22) until 11.59pm on Tuesday (June 23).
It will cover parts of South Wales, including Blaenau Gwent, Newport, Monmouthshire, Cardiff, and the Vale of Glamorgan.
Temperatures are expected to reach 30°C in some parts, while it will remain above 20°C overnight.
These high temperatures are set to have a “widespread impact” on people and infrastructure.
Amber warning of extreme heat affecting Wales https://t.co/ZvYSZJ5JUv pic.twitter.com/OySxHuOq9g
— Met Office – Wales (@metofficeWales) June 19, 2026
What to expect from the amber weather warning in South Wales
The Met Office said the amber weather warning issued across South Wales is due to a “developing hot spell” which will lead to “widespread impacts on people and infrastructure”.
The extreme heat associated with the amber weather warning is also set to cause:
- An increased risk of water safety incidents as more people visit coastal areas, lakes, and rivers.
- Adverse health effects, including sunburn or heat exhaustion (dehydration, nausea, fatigue), and other heat-related illnesses.
- Delays to road, rail, and air travel, with potential for welfare issues for those who experience prolonged delays.
- Changes in working practices and daily routines.
- An increased chance that some heat-sensitive systems and equipment may fail, leading to power cuts and the loss of other services to some homes and businesses.
What different Met Office weather warnings mean
A Met Office spokesperson added: “Following very warm weather on Sunday, very high temperatures are expected on Monday and Tuesday and will likely bring widespread impacts to people and infrastructure.
“In addition to high daytime maxima, temperatures overnight will remain very warm, especially in larger urban areas, and it will also feel humid.
“Temperatures are likely to reach the mid-30s Celsius in places on Monday and Tuesday.
“Some places, particularly in urban areas, may see temperatures remain above 20 Celsius overnight.
“The very high temperatures may continue across a smaller area into the middle of the week, but there remains some uncertainty regarding the extent of this.”
Everywhere in Wales set to be affected by the amber weather warning
Areas of Wales set to be impacted by the amber weather warning issued by the Met Office are:
- Blaenau Gwent
- Bridgend
- Caerphilly
- Cardiff
- Merthyr Tydfil
- Monmouthshire
- Newport
- Rhondda Cynon Taf
- Torfaen
- Vale of Glamorgan
How to stay safe during the amber weather warning in South Wales
The Met Office has issued advice on how to stay safe during the extreme heat associated with the amber weather warning.
A Met Office spokesperson said: “Keep yourself safe by following these simple steps to reduce the likelihood of the heat making you feel unwell; drink plenty of fluids, keep out of the sun and avoid any exercise between 11am-3pm when the sun is strongest and close curtains in rooms that face the sun.
“If you are going out take water with you, stay in the shade, wear sunscreen and a wide brimmed hat.
“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.
“If using public transport, there are many simple things you can do to keep yourself safe; carry water with you, take a small hand-held battery powered fan, if you feel unwell get off at next stop for some fresh air, dress in light fabrics in light colours to help stay cooler, keep an eye on fellow passengers for signs they may be struggling.
“Help to protect vulnerable people that you know including older people, those with underlying conditions and those who live alone; they may need support to keep cool and stay hydrated.
“If you are worried about your health, or that of somebody you know, ring NHS 111.
“Keep yourself safe whilst enjoying the water in this weather by following these simple steps: enter the water gradually, avoiding jumping or diving straight in, to reduce your risk of cold-water shock, go to a lifeguarded beach or a supervised swimming area, and, if you, or anyone else, get into difficulty in the water, float on your back.
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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.
“Stay up to date with the weather forecast for your area and follow any advice from emergency services and local authorities.”
The amber weather warning will be in place across South Wales from 1am on Monday (June 22) until 11.59pm on Tuesday (June 23).
How do you cope in the heat? Tell us your tips and tricks in the comments below.
