Intensification of Climate Extremes in the Sudanian Zone of Benin: Diagnosis Based on ETCCDI Indices

Marcel Adigbegnon, Rafiatou Bamisso, Henri S. Totin Vodounon, Ernest Amoussou, Basile Assouan Akpovi

Climate indices, Extremes, Tropical nights, Hot nights, Sudanian domain.

Analysis of ETCCDI climate indices at stations in the Sudanian zone of Benin revealed an intensification of pluviometric and thermometric extremes. The dataset comprised daily rainfall and temperature (maximum and minimum) records from 22 rain-gauge stations and two synoptic stations over the period 1981-2025. Extreme rainfall and temperature events were determined using XLSTAT 2018 for the computation of 20 ETCCDI indices derived from Rclimdex 2.0, coupled with the Mann-Kendall trend test. A marked spatial variability in annual precipitation (PRCPTOT) was evidenced, with totals ranging from 750 to 2,000 mm yr-1; the highest accumulations were observed in the southern sector (Savalou, Glazoue, Ouesse), while the lowest values (746-913 mm) were recorded in the extreme north (Karimama and Malanville). Extreme indices further corroborate this intensification: RX5day reached 90-110 mm, R99p exceeded 115 mm, R95p ranged between 60 and 100 mm, while R1day surpassed 35 mm day-1 and the Simple Daily Intensity Index (SDII) exceeded 9 mm day-1 in the southeastern part. Analysis of temperature extremes at Parakou indicated significant increases in tropical nights (TR = 2.15; p = 0.03) and warm nights (TN90p = 4.13; p < 0.001), alongside rising extreme maximum values (TXX = 2.18; p = 0.03; TNX = 2.11; p = 0.03). Furthermore, cold spell duration indices (CSDI) exhibited a significant decline (Z = -3.75; p < 0.001). In contrast, at Kandi, the trends were more moderate, with an increase in warm nights (TN90p = 2.86; p = 0.004) and a significant decrease in extreme minima (TNN = -2.65; p = 0.008). These climatic and bioclimatic trends underscore the vulnerability of human health and point toward the need for sustainable, resilient adaptation strategies for local populations.

Received: 29 May 2026, Received in revised form: 25 June 2026, Accepted: 01 July 2026, Available online: 08 July 2026

10.22161/ijaers.137.1