The UK Government has issued a warning about the potential for extreme heat events as global temperatures continue to rise, outlined in its updated National Risk Register for 2025. The document highlights the risk of temperatures exceeding 40°C in parts of England, including London, with potential disruptions to transportation, workforce attendance, and water supplies.

This 187-page report evaluates a variety of risks ranging from terrorism and cyber attacks to nuclear incidents and weather events.

It assigns a 'significant' impact rating to high-temperature emergencies, with a likelihood rating of three out of five.

The report underscores the increasing probability of extreme heat events due to climate change, predicting extended periods of high temperature affecting up to 70% of the UK population.

A 'reasonable worst-case scenario' suggests potential maximum temperatures above 35°C for five consecutive days, with some areas, particularly in south-eastern, eastern, or central England, possibly experiencing temperatures of 40°C or higher.

The document further warns of severe health impacts, including an expected rise in excess deaths beyond typical summer levels, alongside disruptions to transport, supply chains, power, and water supplies.

Economic and social activities may be affected as changes in everyday behavior, such as working patterns, become necessary.

Moreover, the report mentions that such heatwaves could coincide with other hazards like severe thunderstorms, resulting in flooding, poor air quality, drought, and wildfires.

In a foreword, Cabinet Office Minister Pat McFadden emphasized the government's commitment to transparency, aiming to support resilience-building efforts across the UK. The document is intended to underpin public preparedness guidance available on GOV.UK/Prepare, promoting effective steps for emergency readiness.