Dragonflies occur almost everywhere in Europe, but the highest species diversity is found in the southern half, with the highest numbers in parts of southern France, the footland of the Alps and parts of the Balkan Peninsula. The pattern of diversity can roughly be attributed to temperature and precipitation. From north to south the diversity increases with increasing temperature. It tends to decrease in dryer regions, where the diversity of freshwater habitats is reduced. Examples of such areas include part of the Iberian Peninsula, Italy and the Balkan Peninsula. The high diversity in areas such as southern France, the footland of the Alps and certain parts of the Balkan Peninsula corresponds with areas were Mediterranean species co-occur with species from more temperate climates.
European dragonflies have relatively large ranges compared to the ranges of, for instance, butterflies or grasshoppers. Most species occurring in the northern half of Europe extend from western Europe to Siberia, sometimes reaching as far east as Kamchatka and Japan. The species found in the southern half of Europe tend to have smaller ranges. Out of the 18 endemic European species, all but Cordulegaster bidentata have their main distribution area in the southern half of Europe. Fifteen are either confined to islands, the Balkan Peninsula or the Iberian Peninsula and France.
The distribution of threatened dragonflies in Europe reveals a somewhat different pattern than the depiction of overall species diversity. Eighteen of the 22 threatened (sub)species are almost entirely confined to the Mediterranean. Within Mediterranean Europe, there is a very clear concentration of threatened species in the Balkan Peninsula and Crete, with twelve out of the 22 threatened European (sub)species not occurring in other parts of Europe. A second concentration of threatened species is found on the Iberian Peninsula and in southern France, with four threatened species largely confined to this area.