The Met Office has warned that parts of Wales could experience 'tropical nights' this week, with overnight temperatures failing to drop below 20C, making it difficult for people to sleep and increasing health risks.
What are tropical nights?
According to the Met Office, a tropical night occurs when temperatures remain above 20C overnight. This phenomenon is more commonly associated with Mediterranean climates but is now forecast for parts of Wales during the current heatwave.
Met Office deputy chief forecaster Tom Crabtree said: 'As well as very high daytime temperatures, there will be consecutive nights where temperatures do not drop below 20°C, which is called a Tropical Night. This will make it very hard for people to recover from the daytime heat, exacerbating the heat stress impacts.'
Health impacts and warnings
Health experts emphasize that overnight cooling is vital during extreme heat, allowing the body to recover from hot daytime conditions. When temperatures remain elevated through the night, the risk of heat-related illness increases, particularly for older people, young children, and those with underlying health conditions.
The Met Office has warned that the prolonged spell of heat could have impacts across the wider population, with sleep disruption expected to affect many people even if they are otherwise healthy. Warm, humid conditions are expected to make bedrooms feel particularly uncomfortable, especially in urban areas where buildings and roads retain heat long after sunset.
Forecast details
Temperatures across Wales are forecast to climb well above 35C in many areas this week, with some locations potentially approaching 38C. Weather maps show it will still be 24C in south Wales at 1am on Thursday. Some locations may not fall below 20C or 21C for several consecutive nights.
The combination of exceptionally hot days and tropical nights has prompted the Met Office to issue amber heat warnings covering large parts of Wales. Officials urge people to stay hydrated, keep homes as cool as possible, and check on vulnerable friends, relatives, and neighbours.
Duration and outlook
The hot weather is expected to continue until at least Thursday, although there are signs that cooler Atlantic air could begin moving in from the west later in the week.
