As many as 61,000 people may have died in Europe's sweltering heat waves last summer, according to new research, suggesting countries' heat preparedness efforts are falling fatally short.

The study by researchers from European health institutes estimated that more than 61,600 people died from heat-related causes across 35 European countries from late May to early September 2022, during Europe's hottest summer on record.

The study, published on Monday in the journal Nature Medicine, found that Mediterranean countries — Greece, Italy, Portugal and Spain — saw the highest death rate according to population size.