Rainfall in the West African Sahel has partially recovered since the droughts of the 1970s and 1980s, but the form of this recovery matters as much as its size, since crops benefit from more wet days whereas heavier rainfall causes flooding. Using daily records from ten synoptic stations in Burkina Faso from 1981 to 2023, we examined three dimensions of rainfall (frequency, intensity and duration), assessing trends in ETCCDI indices and in rainy-season onset and cessation dates with the Mann-Kendall test and innovative trend analysis, decadal dynamics by station and climate zone, and extreme events through return levels. Frequency changed most, with wet days increasing at five stations (by two to three days per decade in the north), whereas intensity changed less, rainfall on very wet days rising by 16 to 27 per cent per decade at four stations without a significant increase for the average wet day or the annual maximum, and duration changed least, only the end of the season shifting slightly. Most of this change occurred between the 1980s and the 1990s, early in the south and east and later in the north and Ouagadougou, and we interpret it as a recovery from drought rather than a new rainfall regime; annual totals rose mainly because wet days became more numerous, while heavy rainfall became more frequent without a notable increase in intensity, except in Ouagadougou. Policy-makers should therefore pay particular attention to the frequency of heavy-rainfall days, whose effects on agriculture, dams and towns could be detrimental.
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Yaméogo et al. (2026) studied this question.