Pakistan, Aug. 17 -- For more than a century, cafes in the Italian city of Padua have welcomed customers for an early evening drink, or aperitivo, encouraging them to sit outside and socialise before dinner. As Europe bakes under its fifth heatwave of the year, the traditional 6-7 p.m. slot has all but disappeared as people seek air-conditioning indoors, cutting sales for many hospitality businesses.

Moody's has published estimates that last summer's European heatwaves cost €43 billion ($50 billion) in lost economic output while generating only about €500 million of insured payouts. In Padua, aperitivo often now starts later, "which means that the outdoor seating areas, the terraces, the spaces outside . are left unused and e...