Graphic detail | Hot spots Which are the deadliest European cities in a heatwave? A recent study estimated that a ten-day spell of extreme heat starting on June 23rd killed around 2,300 people in 12 European cities. Since the mid-1990s average temperatures on the continent have risen by 0.53℃ per decade, more than double the global land average of 0.26℃. Italian cities fare particularly poorly: Bologna tops the risk table and among large cities Milan is worst. European cities, % increase in risk of death, by temperature By region Northern NorthernWestern WesternEastern EasternSouthern SouthernThe researchers also found that Amsterdam and London are far deadlier in hot weather than other European cities with similar temperatures.