Cardiff sets new June overnight temperature record

Cardiff recorded an overnight minimum of 23.5C at Bute Park, and the Met Office said the reading was the highest June minimum temperature ever recorded in the UK.

The record came amid a fast-moving heatwave that was already producing unusually high temperatures during the day. Later on June 25, the UK also set a new June daytime temperature record, underlining how broad and persistent the hot spell had become.

A record warm night in Cardiff

The Cardiff reading was recorded at Bute Park, where temperatures did not fall enough overnight to give people much relief from the daytime heat. That matters because warm nights reduce recovery time for the body and can make heatwaves more dangerous, especially for older people and anyone with existing health problems.

The Met Office said the 23.5C minimum was the highest June minimum ever recorded in the UK. AP also reported the same figure and location, while The Guardian said the Met Office confirmed the Cardiff reading as the new record.

Humidity made the conditions feel even more oppressive, AP reported, especially after dark when people might otherwise expect cooler air and a break from the heat.

Part of a wider heatwave

The Cardiff record was not an isolated event. It landed in the middle of a wider UK heatwave that had already prompted warnings from forecasters about possible record-breaking June temperatures and tropical nights.

Earlier in the week, the UK had already set a new June daytime temperature record, and later coverage on June 25 reported a further new high of 36.4C at Yeovilton in Somerset. Together, the daytime and overnight records showed the intensity of the heatwave on both sides of the daily temperature cycle.

The Guardian also reported that the Met Office extended its red extreme-heat warning into Friday, and that the UK Health Security Agency extended its red heat-health alert by 24 hours to 11pm on Friday.

Public-health and infrastructure strain

Coverage across the UK reported knock-on effects from the heatwave, including school closures, rail disruption, and pressure on hospitals and other public services. The Cardiff record added a clear data point to what was already becoming a public-health and infrastructure story, not just a weather one.

The stakes are higher when nights stay hot. Public-health officials have long warned that limited overnight cooling is especially risky because the body gets less time to recover before the next day of heat arrives.

That is why the Cardiff record matters beyond one city. It is part of a broader pattern of persistent warmth that can build stress across health services, transport networks and everyday routines.

What officials are watching next

Forecasters had warned before the event that record-breaking June heat could produce tropical nights, and the Cardiff minimum now appears to have borne that out.

The main open questions are whether the Cardiff reading remains provisional or is fully ratified, whether any other overnight records are revised, and how long the red heat warnings stay in place.

Officials are also watching for further disruption as the heatwave continues, including new reports on transport, schools and hospital pressure. The Cardiff record suggests the hot spell is still capable of producing new extremes, even after the daytime temperature record has already fallen.