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. The study tests 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. 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. Jadranska Hrvatska emerges as the most seasonally concentrated non-island region in the sample. The fixed effects results indicate that a higher hotel accommodation share is significantly associated with lower seasonality, while the COVID-19 years significantly increased seasonal concentration without producing a lasting structural shift after 2022. International tourism dependency is not significant in the within-region specification, and island geography is only weakly supported in the random effects model. The study contributes to comparative destination research by operationalising the Gini coefficient as a dependent variable in a regional panel framework and provides policy-relevant evidence for supply-side desezonalisation strategies in Mediterranean EU tourism regions.