González-Hidalgo et al. (2026) Is daily extreme rainfall increasing in the Mediterranean basin? A critical review of the evidence

Identification

• Journal: Earth-Science Reviews
• Year: 2026
• Date: 2026-01-31
• Authors: José Carlos González-Hidalgo, Santiago Beguería
• DOI: 10.1016/j.earscirev.2026.105409

Research Groups

• Department of Geography, Zaragoza University, Spain
• Estaci´on Experimental de Aula Dei (EEAD), Consejo Superior de Investigaciones Científicas (CSIC), Spain
• Laboratorio de Climatología y Servicios Clim´aticos, Spain
• IUCA, Universidad Zaragoza, Spain

Short Summary

This review synthesizes 175 peer-reviewed studies on daily extreme precipitation trends in the Mediterranean basin (1980-2025), revealing no generalized basin-wide intensification but rather substantial spatial and temporal heterogeneity, with localized increases in some areas and stable or decreasing trends elsewhere.

Objective

• To critically review and synthesize published research on trends in daily extreme precipitation events across the Mediterranean basin between 1980 and 2025, documenting the diversity of findings without assessing data or method quality.

Study Configuration

• Spatial Scale: Mediterranean basin, encompassing parts of Europe, North Africa, and the Middle East, with detailed sub-regional analyses for countries like Italy, Spain, France, Morocco, Algeria, Tunisia, Egypt, Israel, Jordan, Cyprus, Türkiye, Bulgaria, Romania, Moldova, Ukraine, Greece, Serbia, Montenegro, Croatia, and Slovenia.
• Temporal Scale: The review covers studies published between 1997 and 2024, examining trends over periods generally from 1980 to 2025. Individual studies analyzed periods ranging from 13 to 157 years, with a modal duration of 49 years, mostly starting after 1950.

Methodology and Data

• Models used: Not applicable; the review focuses exclusively on studies based on observed daily precipitation data, explicitly excluding analyses based on sub-daily data, simulations, or projections.
• Data sources: Systematic compilation of 175 peer-reviewed studies identified using standardized keyword searches in major bibliographic databases (Scopus, Web of Science). The review relies on direct quotations from the abstract, main text, or conclusions of each paper regarding extreme precipitation trends. Studies reviewed employed various extreme precipitation indices, including fixed thresholds (e.g., R10mm, R20mm, R25mm), percentile-based indices (e.g., R95p, R99p, R95pTOT), annual maxima (e.g., RX1day, RX5day), and other metrics (e.g., SDII, DPCI, RPx).

Main Results

• No generalized basin-wide intensification of extreme daily precipitation events has been observed across the Mediterranean. Trends are spatially heterogeneous and often statistically insignificant, with non-significant results prevailing in inland and many southern regions.
• Approximately one-third of the reviewed studies (n = 57) reported increases, another third indicated no significant change (n = 43) or mixed results (n = 43), and a smaller fraction showed decreases (n = 32).
• Positive trends are regionally concentrated in northern Italy, southern France, the eastern Spanish Mediterranean coast, and some areas of northern Maghreb, where increases in daily maxima and high-threshold events (>100 mm/day) have been documented, particularly since the 1980s.
• In much of North Africa, Eastern Europe, and the Eastern Mediterranean, trends are predominantly flat or decreasing, and rarely statistically significant, with many studies pointing to stationarity in extreme rainfall indicators.
• A common finding is a decline in the number of wet days in many parts of the basin (e.g., Italy, Spain), often accompanied by an increase in precipitation intensity, suggesting a shift toward fewer but more intense events rather than a basin-wide intensification.
• The lack of a robust or spatially coherent signal is not systematically dependent on the type of extreme precipitation index used.

Contributions

• Provides the first comprehensive synthesis of observed trends in daily extreme precipitation across the entire Mediterranean basin, compiling 175 peer-reviewed studies.
• Systematically documents reported findings without reinterpretation, highlighting spatial and temporal patterns, and areas of consensus and disagreement.
• Challenges the widespread generalization that extreme precipitation is uniformly increasing in the Mediterranean, aligning with the nuanced regional assessments of the IPCC AR6.
• Underscores the critical need for harmonized methodological frameworks, basin-wide collaborative data efforts, and high-resolution analyses to improve comparability and understanding of regional hydroclimatic risks.

Funding

• Government of Arag´on grant “E02-17R: Geoenvironmental and Global Climate Change Research Group”.

Citation

@article{GonzálezHidalgo2026Is,
  author = {González-Hidalgo, José Carlos and Beguería, Santiago},
  title = {Is daily extreme rainfall increasing in the Mediterranean basin? A critical review of the evidence},
  journal = {Earth-Science Reviews},
  year = {2026},
  doi = {10.1016/j.earscirev.2026.105409},
  url = {https://doi.org/10.1016/j.earscirev.2026.105409}
}