Unconditional and Conditional Event Attribution of the 2025 Vuli/Deyr/Hageya, Short Rains (OND) Drought in East Africa

2025 has been the third warmest year on the observational record globally, while the past decade has been the warmest on record. Accelerating climate change is altering the hydrological cycle, with associated extreme events - including droughts, floods, and compound multivariate extremes - occurring with increasing frequency and intensity in many regions of the world.  

The 2025 October–November-December (OND), short rains (Vuli/Deyr/Hageya) season largely disappointed across East Africa, with major drought hotspots involving highly vulnerable regions in Somalia, eastern Kenya, and southern Ethiopia. Many areas received well under 60% of climatological precipitation level, with patches even below 30%, and some locations ranking among the driest in the satellite-era record (roughly since 1979). This substantial rainfall deficit, amplified by unusually high near-surface air temperature, rapidly degraded rangelands and diminished water availability, driving livestock stress and low crop yields. Additionally, in Somalia, the OND drought contributed to population displacements and heightened need for humanitarian aid.  

We analyse the dynamic and thermodynamic drivers of the 2025 OND, Vuli/Deyr/Hageya drought in East Africa. Using a multi-method attribution framework, we assess the influence of anthropogenic climate change on the development of these high-impact drought conditions, with the strongest signal magnitude in the eastern Horn of Africa. We combine multiple observational and reanalysis datasets with large ensembles of bias-corrected CMIP6 historical simulations and future projections under SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios. This enables us to evaluate the roles of climate-change indices and internal climate variability modes – most importantly ENSO and IOD - in shaping this extreme hydrological event on subseasonal to seasonal timescales.  

Additionally, we use the Met Office HadGEM3-A attribution system to quantify the extent to which anthropogenic forcing has altered the probability and intensity of such class of meteorological drought in the region. We consider both unconditional and circulation-conditioned attribution perspectives. Preliminary results indicate a significant contribution of climate change to the likelihood and intensity of the 2025 Vuli/Deyr/Hageya drought over regions in Ethiopia, Kenya, and Somalia that would greatly benefit from adaptation measures.