Temporal and spatial patterns of severe warm harmattan (SWH) events in Northern Nigeria

Abstract

This study examined the temporal and spatial patterns of Severe Warm Harmattan (SWH) events in Northern Nigeria from 1965 to 2024. Monthly minimum temperatures for the harmattan seasons, spanning November to February, were collected for seven stations in Northwestern Nigeria, namely Birnin Kebbi, Sokoto, Gusau, Katsina, Kano, Dutse, and Kaduna, and for six stations in Northeastern Nigeria, namely Damaturu, Maiduguri, Bauchi, Gombe, Yola, and Jalingo, and analysed across the sixty year study period. A cross-regional comparison and a decadal analysis were conducted, and the Standard Anomaly Index was applied to identify SWH events. The findings revealed that SWH events occurred 142 times in Northwestern Nigeria and 116 times in Northeastern Nigeria, totalling 258 occurrences across Northern Nigeria. In the Northwestern region, Kaduna recorded the highest frequency of SWH events at 31 occurrences, while Sokoto recorded the lowest at 11. In the Northeastern region, Gombe recorded the highest at 24 occurrences, while Jalingo recorded the lowest at 17. SWH events were concentrated in November and February, the transitional months of the harmattan season. Among decades, the first decade exhibited the highest occurrence in Northwestern Nigeria, while the 2005 to 2014 decade showed the highest frequency in the Northeastern region. The decadal frequencies revealed no uniform trend between the two regions, yet all stations documented anomalous warming, underscoring the growing influence of climate change on the harmattan season and the attendant implications for public health and adaptation planning.