Comparing heat deaths to gun deaths is beyond absurd, but people keep repeating it because it's a good soundbite that makes the US seem good and the EU seem bad. It's like ranking places by comparing flu deaths to war deaths. Gun-related deaths are direct and attributable. The heat deaths reported are counted as 'excess deaths'. The number of people who actually die from the heat is small if compared to the overall number. Excess deaths counts all cases where people's existing issues were exacerbated by the high temperatures which eventually pushes them over the edge - old age, heart disease and the like. Heat mostly doesn't make healthy people drop dead in the streets, unlike a direct cause like guns. It diminishes everyone's health which makes already vulnerable people die earlier of their pre-existing conditions than they otherwise could have. These are different metrics.