Characterizing Heatwave Dynamics in Burkina Faso Using Multi-Satellite Assimilated ERA5 Reanalysis

Global climate change and anthropogenic forcing have intensified extreme heatwave activity across the West African Sahel. However, quantifying heatwave severity in da-ta-sparse regions like Burkina Faso—which spans distinct semi-arid and Sudanian climatic zones, remains a challenge. In this study, we adapted the daily Heat Wave Magnitude Index (HWMId) by calculating calendar-day-specific 25th and 75th percen-tile thresholds alongside a 40 °C absolute boundary using multi-satellite assimilated ERA5 2-meter maximum air temperature (T2m) reanalysis data from 2001 to 2025. The resulting heatwave magnitude time series was evaluated against the Relative Oceanic Niño Index (RONI) to investigate delayed teleconnections with the El Niño–Southern Oscillation (ENSO). The analysis identified a peak teleconnection when RONI led Burkina Faso heatwave conditions with an 8-month lag. Independent of background global warming, equatorial Pacific ENSO dynamics accounted for approximately 14% of the residual variance in regional heatwave severity. These findings demonstrate that satellite-assimilated reanalysis, combined with detrended ENSO metrics, provides an actionable 8-month seasonal forecasting window to support disaster response and public health preparedness across the Sahel.