The Met Office has issued an Amber heat warning for southern England and southeastern Wales in June 2026. Temperatures are forecast to reach 38°C, which would break the UK's June temperature record, according to the Met Office.

An Amber warning is the Met Office's way of flagging dangerous weather. It means problems are expected: buses and trains may run late or stop, hospitals will be under pressure, and some people — especially elderly people and those with health conditions — are at risk.

To put 38°C in perspective: the UK's June record is 35.6°C. But even more striking, the country's highest temperature ever recorded is 40.3°C, set in Lincolnshire in July 2022. That was the first time 40°C had been recorded anywhere in the UK. If June reaches 38°C, we'll be close to that historic level.

A Warming Pattern

This warning comes as part of a larger trend. In 2025, the UK experienced its warmest year on record. That means this June heat event is not a one-off surprise — it fits into a pattern of rising temperatures.

Heat waves in June used to be rare in Britain. The Atlantic Ocean normally keeps the UK cool. But the jet stream — a river of air high in the atmosphere that guides weather systems — is moving northward. When it weakens in summer, hot air from the Sahara or mainland Europe can push directly into Britain without being blocked by Atlantic storms.

This matters for more than just thermometers. Buses and trains have to slow down. Power plants need more electricity for air conditioning. Hospital emergency departments get busier. When a heat alert covers a wide area like this one does, all these pressures happen at the same time.

What Happens Next

The Met Office extended this warning rather than just issuing it in the first place. That signals their computer models are confident in the forecast. The heat pattern looks locked in.

Whether the temperature actually hits 38°C will depend on the exact track of the weather system and on how warm the nights get. Night-time warmth matters because people's bodies don't cool down overnight — and that lack of cooling is linked to deaths, sometimes more so than daytime heat peaks.

Looking ahead, the question facing policymakers is simple: we need to adapt. Most UK houses are built to keep warmth in, not let it out. Air conditioning is rare. Buildings, roads, and power systems were designed for cooler weather. The gap between what we have and what we need is well-known, but change has been slow.

If 38°C is reached, it will add pressure to that conversation. But the real signal is already here: the warmest year on record in 2025, June records now under threat, and warnings that cover so much of the country that critical services everywhere feel the strain at once.