Cardiff has broken its highest June minimum temperature record, with the mercury not dropping below 22.4°C overnight, surpassing the previous record of 21.7°C set in 1898. The milestone comes as a savage heatwave continues to bake parts of the UK, with temperatures expected to climb further in the coming days.
Record-Breaking Overnight Heat
The Met Office confirmed that the temperature at Cardiff's Bute Park weather station remained above 22.4°C throughout the night of June 24-25, smashing the previous June record by 0.7°C. This marks the highest minimum temperature ever recorded in June for the Welsh capital, a record that had stood for 128 years.
According to Met Office meteorologist Alex Deakin, “The warm night is a clear indicator of the intensity of this heatwave. When minimum temperatures remain this high, it puts additional strain on the body, especially for vulnerable people.”
Heatwave Intensifies Across the UK
The record comes as a heatwave dubbed “Cerberus” by some media outlets continues to affect large swathes of the UK. Temperatures in parts of England and Wales have soared above 35°C, with forecasts suggesting they could reach 38°C in some areas by the weekend. The UK Health Security Agency has issued a Level 3 heat-health alert for much of England, urging people to stay hydrated, avoid direct sun during peak hours, and check on elderly neighbours.
In Wales, Natural Resources Wales has warned of increased risk of wildfires, with several small blazes already reported in dry grassland areas. The heatwave has also led to disruptions on rail networks, with speed restrictions imposed on some routes due to the risk of tracks buckling.
Climate Context and Expert Warnings
Scientists have linked the extreme heat to human-induced climate change. Dr. Friederike Otto, a senior lecturer in climate science at Imperial College London, said, “This heatwave is exactly the kind of event that climate change makes more likely and more intense. The record warm night in Cardiff is a stark reminder that global warming doesn't just affect daytime highs but also overnight lows, which can be deadly.”
The Met Office's State of the UK Climate report for 2025, published earlier this year, noted that the UK's average temperature has risen by about 1.2°C since the late 19th century, with heatwaves becoming more frequent and severe. The report also highlighted that the number of tropical nights—where the temperature stays above 20°C—has increased significantly in recent decades.
Impact on Health and Infrastructure
Public health officials have expressed particular concern about the lack of relief overnight. “When temperatures don't drop, the body has no chance to recover from daytime heat stress,” said Dr. Agostinho Sousa, head of extreme events and health protection at the UK Health Security Agency. “We are advising people to keep their living spaces cool, use fans or air conditioning if available, and to avoid strenuous activity during the hottest parts of the day.”
Hospitals in affected areas have reported an uptick in heat-related admissions, including cases of heat exhaustion and dehydration. The National Grid has said it is monitoring electricity demand closely, as air conditioning use surges. So far, no power outages have been reported, but the grid operator has asked consumers to use energy wisely.
Looking Ahead
The heatwave is expected to persist into early next week, with a slight chance of thunderstorms bringing some relief. However, forecasters warn that any storms could bring lightning that might ignite further fires. The record broken in Cardiff is likely to be one of many as the heatwave continues to rewrite weather history.
