Record heat linked to unprecedented fall in UK milk deliveries

UK dairy farms delivered the equivalent of 25 million fewer pints of milk during the May and June heatwaves, marking the first major heat-related disruption identified in 19 years of delivery data.

Analysis by the Energy and Climate Intelligence Unit found that record temperatures coincided with the sharpest single-day falls in farm milk deliveries recorded during a heatwave since 2008.

Deliveries fell almost 4% below the previous week’s average on 26 May, equivalent to around 3.2 million pints, with the estimated shortfall across the full May heatwave reaching 8.3 million pints.

On 26 June, deliveries fell by 4.3%, equivalent to around 3.3 million pints. Across the nine-day June heatwave, the cumulative shortfall was estimated at 9.4 million litres, or 16.5 million pints.

The figures represent milk that was not delivered compared with recent production patterns, rather than milk known to have been produced and wasted.

The ECIU stressed that the decline did not amount to a national supply crisis, but said it could be an early warning that extreme heat is joining severe cold as a risk to dairy production.

May is normally the peak month for UK milk output, with deliveries typically rising by between 2% and 4% compared with April. In May 2026, however, the increase was just 0.08%.

Leicestershire dairy farmer Ruth Grice said the heat had a visible effect on her herd.

“The heat in May had a real impact. The cows were hot and bothered and were obviously prioritising staying cool over producing milk,” she said.

“When we did the night checks they were standing around the water troughs for relief from the heat, whereas normally they would be quietly sleeping or ruminating.”

She warned that the consequences extended beyond lower yields, adding: “It’s not just the drop in milk production; heat also affects the cows’ fertility, which is crucial for a dairy farm’s viability.”

Her farm is creating additional shade by planting hedgerows and large native trees in areas used by the herd during the hottest parts of the day, although prolonged dry conditions are making new planting increasingly difficult to establish.

“There are technological solutions like fans in the sheds, but they are very expensive to install and maintain,” she said.

“For us, working with nature has to be at the heart of our future.”

Dairy cows are particularly sensitive to combinations of high temperatures and humidity, which can reduce feed intake, depress milk yields and affect fertility.

During the May heatwave, conditions reached levels associated by researchers with milk-production losses of up to 20% per cow.

Extreme temperatures can also place additional pressure on farm cooling systems and refrigerated transport, increasing the risk of spoilage or rejected deliveries.

Tom Cantillon, senior analyst at the ECIU, said: “The May and June heatwaves look like the clearest signals yet that extreme heat is impacting the UK’s dairy industry.”

He warned that both livestock and the infrastructure needed to keep dairy products cold faced growing risks as heatwaves became more severe.

“This is another example of climate change impacting the resilience of our food system,” he said.

The Cold Chain Federation said businesses had established plans to protect food safety and quality during disruption, but warned that much of the country’s refrigerated infrastructure was not designed for temperatures approaching 40°C.

Policy manager Maddy Coupe said: “A significant amount of the UK’s cold chain infrastructure was not built for the 40°C temperatures we are increasingly experiencing, with around half of cold storage facilities over 20 years old.”

“As temperatures continue to rise, these temperature-controlled systems have to work harder to maintain the safety, quality and availability of food products including milk and dairy,” she added.

The ECIU said every major weather-related disruption identified in the previous 19 years of delivery data had been linked to extreme cold.

It said the emergence of a comparable heat-related fall suggested dairy farmers and the wider supply chain may need to prepare for increasingly severe pressure during future heatwaves.