The 2023 record-breaking heatwave in North Africa: characteristics and driving mechanisms

Abstract

Global mean temperatures reached unprecedented levels in 2023, and large parts of the world experienced prolonged and recurrent heatwave conditions, resulting in severe consequences for public health and socioeconomic systems (Perkins-Kirkpatrick et al., 2024). North Africa was among the regions most severely affected. However, quantitative assessments of the spatial extent and seasonal progression of record-breaking heatwaves over North Africa remain limited. This study uses the Excess Heat Factor (EHF, Nairn et al. 2009) to characterize heatwaves across North Africa in 2023, examining their spatial patterns and seasonal evolution with reference to the past five decades. North Africa experienced exceptionally warm conditions in 2023 characterized by prolonged heatwaves and a markedly expanded spatial extent compared with the 1972–2022 reference period. Indeed, temperature anomalies reached up to 5K over most of the region, with the strongest differences occurring during the boreal autumn (SON). Notably, approximately 35% of the study domain experienced the highest seasonal mean near-surface temperature on record since 1972. The heatwave analysis revealed pronounced anomalies in 2023 relative to the baseline climatology; the event frequencies ranged from 2 to 5 events per year, and their duration exceeded the reference by 4 to 7 days across large parts of the domain during summer (JJA) and autumn (SON), particularly over Morocco, the central Sahara, and surrounding regions. In addition, record-breaking daily maximum temperatures (Tmax) were detected at multiple timescales over the 50-year record. During two major episodes in 2023, the spatial extent affected by these record-breaking conditions exceeded 4 × 10⁶ km², occurring from 25 July to 5 August and from 25 October to 10 November, respectively.These hot events were also assessed in terms of related large-scale atmospheric circulation. The mid-atmosphere conditions were characterized by positive geopotential height anomalies at 500 hPa, with an anomalous ridge centered over northern Morocco and Algeria bringing persistent atmospheric blocking and enhanced warm air advection, favoring the development and persistence of extreme surface temperatures. Concurrently, temperature anomalies at 850 hPa ranged from 2 to 4 K over northeastern Morocco, Algeria, and Egypt, while more moderate anomalies of approximately 1 to 2 K were observed along the Atlantic coasts and across the southern Sahara. These findings highlight the exceptional severity, persistence, and spatial extent of the 2023 heatwaves in North Africa, underscoring the region’s increasing vulnerability to extreme thermal events under ongoing global warming.References:Perkins-Kirkpatrick, S., Barriopedro, D., Jha, R. et al. Extreme terrestrial heat in 2023. Nat Rev Earth Environ 5, 244–246 (2024). https://doi.org/10.1038/s43017-024-00536-yNairn, J., R. Fawcett, and D. Ray, 2009: Defining and predicting excessive heat events: A national system. CAWCR Tech. Rep. 017, 83–8