Strong winds in Mediterranean Cyclone Harry mostly strengthened by human-driven climate change

Contact Authors

• Davide Faranda (IPSL-CNRS, France) - davide.faranda@lsce.ipsl.fr  - EN/FR/IT

• Carmen Alvarez-Castro (UPO Sevilla, Spain) – mcalvcas@upo.es  – ES/EN/IT

• Alice Portal (CNR, Italy) –  a.portal@isac.cnr.it  – IT/EN

• Marco Reale (OGS, Italy) -mreale@ogs.it – IT/EN

• Haosu Tang (University of Sheffield, UK) – haosu.tang@sheffield.ac.uk  – ZH/EN

• Tommaso Alberti (INGV, Italy) tommaso.alberti@ingv.it  – IT/EN

• Meriem Krouma (IVM, VU, Netherlands)  m.krouma@vu.nl, – EN/AR/FR

• Valerio Lucarini (Leicester University, UK) – v.lucarini@leicester.ac.uk  – IT/EN

• Erika Coppola (ICTP, Italy) - coppolae@ictp.it - IT/EN

Citation

• Faranda, D., Alvarez-Castro, M. C., Portal, A., Reale, M., Tang, H., Alberti, T., Krouma, M., Lucarini, V., & Coppola, E. (2026). Strong winds in Mediterranean Cyclone Harry mostly strengthened by human-driven climate change. ClimaMeter, Institut Pierre Simon Laplace, CNRS. https://doi.org/10.5281/zenodo.18377082 

Press Summary

• Mediterranean depressions similar to Cyclone Harry are up to 8  km/h (≈ 15%) windier today than in the past. 

• This event was associated with exceptional meteorological conditions.

• We mostly ascribe the  stronger winds of Cyclone Harry to human-driven climate change and natural climate variability likely played a modest role.

Event Description

Cyclone Harry affected Sicily, Sardinia and Calabria between 19 and 22 January 2026, bringing exceptionally severe weather conditions to large parts of the affected areas . The storm was characterised by intense and persistent rainfall, very strong winds, and extreme waves along both the Ionian and Tyrrhenian coasts. In eastern Sicily, cumulative rainfall totals led to flash floods and river overflows, inundating urban areas, damaging homes and businesses, and forcing precautionary evacuations in several municipalities. Coastal areas were particularly exposed, with waves up to 9–10 metres causing significant coastal erosion, damage to promenades, railways and port infrastructure, and flooding of low-lying seafront districts.

The economic impact of Cyclone Harry has been severe. Initial assessments by regional authorities and national media estimate damages for example in Sicily between 700 million and more than 1 billion euros, including losses to transport infrastructure, coastal facilities, tourism, fisheries, and agriculture. Roads and railway lines were temporarily closed due to flooding, landslides, and debris, while airports and ports suspended operations during the peak of the storm. Several municipalities ordered the closure of schools, public buildings, and non-essential activities as a preventive measure. 

Despite the violence of the storm, no fatalities were reported . This outcome has been widely attributed to the timely issuance of red weather alerts and the effective coordination between civil protection authorities, municipalities, and emergency services. Early warnings, mobility restrictions, and targeted evacuations significantly reduced exposure to the most dangerous conditions, demonstrating the crucial role of impact-based forecasting and preparedness in limiting casualties during extreme weather events. Local authorities described some coastal areas as temporarily unrecognisable due to flooding and storm damage, underlining the long recovery process ahead. Cyclone Harry has reinforced concerns about the vulnerability of Mediterranean coastline to intense winter cyclones and the growing need for long-term adaptation strategies, particularly in coastal and flood-prone zones.

The meteorological conditions were characterized by persistent and strong negative surface pressure anomalies, reaching approximately −15 hPa over Tunisia. Near-surface temperature anomalies exhibited a mixed pattern, with scattered positive and negative values locally exceeding ±5 °C across large parts of the affected region. This spatial structure is consistent with the presence of a well-developed frontal system. Daily precipitation totals locally exceeded 150 mm, with the most intense rainfall concentrated along coastal areas and over the interior highlands. Sustained near-surface wind speeds locally reached up to 100 km/h during the event. A pronounced easterly flow played a key role in enhancing moisture advection from the Ionian Sea, contributing to prolonged and intense rainfall over the Eastern, Ionian-facing part of the island.

Climate and Data Background for the Analysis

Mediterranean cyclones are projected to exhibit changes in their wind characteristics under climate change, according to assessments synthesised in the IPCC AR6 Working Group I report. While the total number of Mediterranean cyclones is expected to decrease or remain stable, the most intense systems are projected to produce stronger near-surface winds. This intensification is linked to enhanced horizontal pressure gradients and increased atmospheric instability associated with a warmer climate. These stronger winds combined with sea level rise and increased frequency of extreme total water level events in the Mediterranean sea are expected to exacerbate coastal flooding, including storm surge, wave damage, and wind-related infrastructure losses, particularly in exposed coastal regions of the central and eastern Mediterranean.

Our analysis approach rests on looking for weather situations similar to those of the event of interest having been observed in the past. For this event we have low confidence in the robustness of our approach given the available climate data, as the event is very exceptional in the data record.

ClimaMeter Analysis 

We analyze here (see Methodology for more details) how events similar to the meteorological conditions leading to Cyclone Harry have changed in the present (1988–2025) compared to what they would have looked like if the event had occurred in the past (1950–1987) in the region [9°E–21°E, 31°N–41°N]. From the surface-pressure changes  it appears that the shape of the pressure low in the analogues changes from past to present (extending further north in the present), but the intensity of the central pressure minimum is not significantly different. Temperature changes show a robust warming signal, with increases of about +1 to +2 °C over Sicily and surrounding areas, consistent with a warmer background state during the event. Precipitation changes are not uniform but suggest locally wetter conditions. Wind speed changes show the clearest dynamical intensification: present minus past indicates stronger winds over the Ionian-facing side of Sicily and the adjacent sea, with increases commonly around +4 to +8 km/h and local maxima near the eastern coastal sector. This pattern is consistent with an enhanced easterly to southeasterly low-level flow, favouring stronger onshore wind impacts and more efficient moisture advection toward eastern Sicily. Similar past events do not indicate a major seasonal displacement. Changes in urban areas (notably Catania and Messina, and also Cosenza in southern Italy) are consistent with the regional signal, showing warmer conditions and stronger winds compared to past analogues, implying increased exposure to wind-related damage and to compounding coastal hazards such as waves and surge during comparable cyclonic configurations today.

Finally, we find that sources of natural climate variability, notably the Pacific Decadal Oscillation, may have only partly influenced the event. This means that the changes we see in the event compared to the past may be mostly due to human-driven climate change.

Conclusion

Based on the above, we conclude that meteorological conditions associated with Mediterranean Cyclone Harry were stronger than comparable past events, with near-surface wind speeds increased by up to 8 km/h (≈ 15%). We interpret this as an event driven by exceptional meteorological conditions whose intensity has been amplified by human-driven climate change, through a warmer background state and strengthened circulation.