Drought analysis in Pemba district, northern Mozambique (1991 – 2023) using the Standardized Precipitation Index (SPI)

Abstract Drought monitoring is essential for climate adaptation and water resource management in sub-Saharan Africa. This study provides the first comprehensive characterization of drought patterns in the Pemba district, Cabo Delgado Province, northern Mozambique, using the Standardized Precipitation Index (SPI) calculated from 33 years (1991-2023) of NASA POWER satellite-derived monthly total precipitation data. SPI values were computed using the DrinC software at multiple time scales (1, 3, 6, 9, and 12 months) following the standard gamma distribution methodology recommended by the World Meteorological Organization. Results show that the region experienced 12 distinct drought episodes at the 12-month scale, with the most severe event occurring in February 2006 (SPI-12 = −2.59, extremely dry category). The longest drought episode lasted 12 months (February 2009 to January 2010) with a minimum SPI-12 of −2.23. Extreme drought conditions (SPI ≤ −2.0) occurred in 2.9% of months, while normal conditions (−0.99 to 0.99) prevailed in 72.5% of the study period. The mean annual precipitation was 1,037.1 mm, with a coefficient of variation of 27.1%, indicating substantial inter-annual variability characteristic of tropical savanna climates. These findings provide critical baseline information for drought early warning systems, agricultural planning, and climate adaptation strategies in northern Mozambique.