When Extreme Heat Becomes the Norm in Ouagadougou, Burkina Faso
Jean David Ouezzin Coulibaly
*
Climate Analytics Africa Office, Rue Lawson-Boe, BP 81733, Lomé, Togo.
Issouf Traore
University Institute for Initial and Continuing Education (IUFIC), Thomas Sankara University, Avenue Père Joseph Wresinski, Patte d'Oie, Ouagadougou, Burkina Faso.
*Author to whom correspondence should be addressed.
Abstract
Aims: To analyse the evolution of maximum temperatures and characterise thermal extremes in Ouagadougou between 1973 and 2025.
Study Design: Retrospective observational time-series study based on daily meteorological observations and extreme value analysis.
Place and Duration of Study: Ouagadougou, Burkina Faso, using observations covering the 1973-2025 period.
Methodology: Daily data from the Global Historical Climatology Network-Daily (GHCN-D) were analysed. The annual 90th percentile of TMAX (q90_TMAX) was assessed using the Mann-Kendall trend test and Sen's slope. Annual maxima were modelled with the generalised extreme value (GEV) distribution, while a generalised Pareto distribution (GPD) was fitted to exceedances above q90_TMAX. Model adequacy was assessed using graphical diagnostics and the Anderson-Darling test.
Results: The mean daily maximum temperature was 35.46 °C and the observed maximum reached 49.6 °C. q90_TMAX showed a highly significant increasing trend (τ = 0.437; P < .001), with Sen's slope estimated at 0.38 °C per decade (95% CI: 0.25-0.50). The GEV fit to annual maxima was not rejected at the 5% level (Anderson-Darling = 2.3496; P = .060), whereas the GPD fit was rejected (P < .001). GEV return levels were 42.90 °C at 2 years, 44.42 °C at 5 years, 45.33 °C at 10 years, and 47.10 °C at 50 years.
Conclusion: Extreme heat has become a recurrent hazard in Ouagadougou, highlighting the need to strengthen early warning, urban planning and health preparedness on a sustained basis.
Keywords: Extreme temperatures, extreme heat, extreme value theory, climate change, Ouagadougou