Britain’s £4.4bn heatwave bill may be far bigger than the headline figure suggests

• Heatwaves are estimated to have wiped £4.4 billion from UK economic output by the end of July.
• London has taken the biggest hit, with the City of London alone facing an estimated £435 million loss.
• Verdant warns the cumulative cost could reach at least £25 billion by 2030 if heatwaves intensify at the same rate.

Britain’s repeated summer heatwaves have already cost the UK economy an estimated £4.4 billion, as extreme temperatures reduce worker productivity and cause infrastructure and equipment to fail, according to new analysis from think tank Verdant.

The figure covers the impact of heatwaves through the end of July and comes as the UK faces another spell of extreme heat in August. The Met Office has warned that temperatures could reach 38C, while the country is on course for its hottest summer on record.

The economic damage is not simply about people finding it harder to work in hot offices or outdoor workplaces. Verdant's estimate includes lost output when workers become less productive and when infrastructure and equipment are affected by excessive heat.

The think tank's earlier estimate put the cost of the June heatwave alone at £2.36 billion. After adding July's losses, the estimated bill has risen to £4.4 billion. Verdant says its calculation is conservative because it does not include wider costs such as increased energy use, longer-term investment effects or broader economic consequences.

That means the £4.4 billion figure should not be read as the total cost of the summer's heat. It is an estimate of direct economic losses from reduced productivity and heat-related disruption.

London is carrying the biggest bill

The impact has been particularly severe in London and the south of England, where temperatures have been among the highest.

The City of London is estimated to have lost £435 million in economic output this year because of the heat. Westminster follows at £371 million, while Tower Hamlets is estimated to have lost £186 million and Camden £181 million.

Birmingham was the only area outside London to make Verdant's top 10, with an estimated £60 million loss.

The concentration of losses in London is significant because the capital has a large share of the UK's financial and professional services economy. Even where work can technically continue during a heatwave, lower concentration, disrupted sleep, illness and uncomfortable working conditions can affect how much gets done.

Research from the Grantham Research Institute at the London School of Economics has also pointed to the productivity impact. Its research into the June heatwave estimated more than £1 billion in lost output, while a survey of 2,000 people found that 3.6 per cent had not worked at all during the week of June 22 because of the heat. The same survey found 87 per cent had experienced at least one health-related effect, including disrupted sleep or dizziness.

The pressure is coming at a time when extreme heat is becoming a more frequent economic concern rather than a one-off disruption. Verdant's analysis uses 30C as a key point at which productivity losses become more pronounced, based on European research linking higher temperatures with lower output.

The bill could become much bigger

Verdant's warning is that this year's £4.4 billion loss could be a sign of a much larger problem if Britain becomes accustomed to hotter summers without changing how workplaces and cities are designed.

If heatwaves continue intensifying at the same rate seen over the past decade, Verdant estimates that heat-related output losses could reach at least £25 billion cumulatively by the end of 2030. The estimate assumes no effective action is taken to reduce the economic impact of extreme heat.

The figure is not a forecast of the UK's entire economic loss from climate change. Verdant specifically describes it as a minimum estimate based on productivity losses from extreme heat, meaning the eventual cost could be higher if other effects are included.

The group is calling for a national maximum working temperature, a heat insurance mechanism for workers unable to work during extreme temperatures, more investment in cooling and changes to the design of towns and cities.

Dr James Meadway, co-director of Verdant, reportedly said the economic costs of climate change were already being felt and were likely to worsen, arguing that the government needed to do more to protect workers and businesses from extreme heat.

The pressure is no longer limited to the workplace. Drought has spread across much of England and all of Wales, while repeated heatwaves have increased the risk of wildfires and put further pressure on water supplies. The government is due to hold an emergency Cobra meeting on August 12 to discuss the wider impact of the extreme weather.

The bigger question for businesses may therefore be less about how to get through one unusually hot summer and more about how much it will cost to operate in a country where extreme heat becomes a regular part of the working year.