Regional Determinants of Tourism Seasonality in Mediterranean EU NUTS–2 Regions: A Panel Analysis Using the Gini Coefficient (2020–2024)

Tourism seasonality remains one of the most persistent structural challenges of Mediterranean destinations, intensifying environmental, economic and social pressures during peak months while leaving tourism capacity underused in the remainder of the year. This paper examines the level, spatial distribution and structural determinants of tourism seasonality in 61 Mediterranean EU NUTS–2 regions from Croatia, Spain, Greece, Portugal and Italy over the period 2020–2024. Using harmonised Eurostat data, annual Gini coefficients are calculated from monthly overnight stays and analysed within a balanced panel of 305 region-year observations, testing whether seasonality is associated with international tourism dependency, hotel accommodation share and island geography, while controlling for regional GDP per capita, tourism intensity and the COVID-19 disruption period. Fixed and random effects models are estimated, with model choice guided by the Hausman test and cluster-robust standard errors applied at the regional level, complemented by a correlated random effects (Mundlak) specification. The results show substantial regional heterogeneity: Greece and Italy record the highest average seasonal concentration, while Spain and Portugal display more balanced patterns, partly due to regions with year-round demand, and Jadranska Hrvatska emerges as the most seasonally concentrated non-island region in the sample. A higher hotel accommodation share is significantly associated with lower seasonality, while the COVID-19 years significantly increased seasonal concentration, with concentration levels returning to recovery-phase values from 2022 onwards; as the panel does not include pre-pandemic baseline years, the findings compare the pandemic phase (2020–2021) with the recovery phase (2022–2024) and do not directly test a return to pre-pandemic equilibrium. The study contributes to comparative destination research by operationalising the Gini coefficient as a dependent variable in a multi-country regional panel framework and provides policy-relevant evidence for supply-side deseasonalisation strategies embedded in integrated destination management.