The outstanding European and Mediterranean heatwave activity during summer 2022

The European summer of 2022 was exceptionally warm in the historical record (since mid-19th century). We show that it was a record-breaking summer at European scales since at least 1500 due to three large-scale atmospheric heatwaves, all concurring with a prolonged dry period over Europe and an intense marine heatwave over the Mediterranean. We evaluate the role of dynamical (atmospheric circulation) and thermodynamical (regional soil moisture and western Mediterranean sea surface temperatures) drivers. Flow analogues of the June 2022 heatwave are used to reconstruct the expected temperatures under different combinations of these thermodynamical drivers and assess their separate and combined influences on the intensity of the event. Results show a measurable intensification of the heatwave event (of ~1 °C) by both dry land and warm sea conditions. We also report asymmetric responses to their combined effects: the influence of warm waters on heatwave intensity is larger when accompanied by dry soils than when soils are wet. • European summer (June-to-August) of 2022 was the warmest since at least 1500. • The Mediterranean displayed the largest Marine HW activity of 1982–2022. • Three European mega-HW events in June, July and August/September 2022. • Flow analogues of the June 2022 HW are used to reconstruct temperatures. • Identified (of ~1 °C) intensification of HW event by both dry land and warm sea.