Fifty years ago, farmers in Italy’s Emilia-Romagna would open barn windows at night to cool cattle in summer. Today, with heatwaves sending temperatures to record highs, those openings remain open round the clock to protect cows—and ultimately their milk, the foundation of the centuries-old Parmigiano Reggiano industry.

“Extreme heat impacts milk’s quality and quantity,” said Nicola Bertinelli, president of the Parmigiano Reggiano Consortium. With temperatures topping 40°C, cows spend more time lying down, eat less, and produce up to 10% less milk. Production of authentic Parmigiano Reggiano is restricted to five provinces, and cows must be fed exclusively with grass and hay grown there. Farmers warned that without rain, grass doesn’t grow and hay can’t be produced, limiting the milk supply needed to make the cheese.

To cope, producers have installed fans and water-mist systems, but those cooling measures have driven energy costs higher. The same pressures are hitting the warehouses where cheese wheels are stored during ageing, which lasts at least 12 months and can extend to three years or longer.

More than 500,000 wheels—worth more than €300 million—are held in two warehouses in the provinces of Reggio Emilia and Modena. During this year’s peak heatwaves, one operator said daily energy consumption rose by about 30%. Efforts to offset the problem include improving cooling systems and boilers, upgrading insulation, and increasing renewable energy.

Behind the warehouses’ walls—known as the “Bank of Parmigiano”—technology and tradition meet. Each wheel undergoes strict quality inspections, including X-ray scans to rule out defects, and experts tap wheels with small hammers weekly to detect flaws that might develop during ageing.

Industry leaders say the stakes are high: the Parmesan business generates an estimated €4.5 billion in annual revenue and supports thousands of jobs, with exports accounting for more than half of global sales. The region’s producers say they want future generations to still be able to eat Parmigiano Reggiano.