Meteorological drought dynamics across Nigeria: Multi-scale SPI insights for climate adaptation

Abstract

Drought remains one of the most pervasive climate-related hazards in Nigeria, posing substantial risks to agriculture, water resources, and socio-economic livelihoods. This study investigates the spatio-temporal dynamics of meteorological drought across Nigeria between 1981 and 2019, addressing the limited availability of multi-scale, station-based drought assessments across the diverse eco-climatic zones of the country. Monthly rainfall data from the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS v2.0) dataset were analysed for 48 meteorological stations representing six eco-climatic zones. Meteorological drought was quantified using the Standardised Precipitation Index (SPI) at 3-, 6-, 9-, and 12-month timescales, computed using an empirical, distribution-free formulation. Mann–Kendall trend analysis and wavelet transform techniques were applied to assess long-term trends and dominant drought periodicities. Results indicate that moderate droughts were the most frequent nationwide, accounting for approximately 7–8% of years across all time scales. In contrast, severe and extreme droughts were less frequent but spatially widespread and episodic. Severe and extreme droughts clustered prominently during the 1980s, 2000s, and 2010s, with the Sahel and Sudan savanna zones emerging as the most drought-prone at longer accumulation periods. Short-term drought extremes (SPI-3), including an exceptionally severe event in 2017 (e.g., Ibadan SPI = − 4.00), highlight increasing vulnerability in humid southern regions, driven largely by rainfall variability rather than sustained deficits. Wavelet analysis revealed dominant drought periodicities at 2–4-year and 8–12-year bands, consistent with large-scale climate oscillations such as ENSO, which is discussed in the context rather than through direct statistical attribution. In general, the findings demonstrate that drought in Nigeria is recurrent, spatially heterogeneous, and multi-scalar in nature. The results highlight an emerging hydroclimatic shift characterised by increased rainfall variability, even in traditionally humid regions, reinforcing the need for drought-resilient agriculture, integrated water resource management, and strengthened early warning systems.