Climatological Study of Relative Humidity Patterns in Maiduguri, Borno State

Relative humidity is a fundamental meteorological variable influencing thermal comfort, evapotranspiration, and disease transmission dynamics in semi-arid environments. This study presents a climatological analysis of relative humidity patterns in Maiduguri, Borno State, using daily morning and afternoon observations recorded at the Maiduguri International Airport meteorological station from 2013 to 2023. Descriptive statistics, seasonal decomposition, and harmonic analysis were applied to characterize the annual cycle, inter-annual variability, and long-term trends in relative humidity. Results reveal a pronounced seasonal cycle, with mean afternoon relative humidity dropping to below 15 percent during the peak harmattan period of December and January, creating conditions conducive to elevated evapotranspiration stress and meningitis transmission. Morning humidity values show comparatively less inter-annual variability than afternoon readings, reflecting the dominance of large-scale monsoon circulation in controlling moisture availability. A statistically non-significant declining trend in mean annual relative humidity is identified over the study period. Spatial comparison with a rural station at Bama reveals consistently higher morning humidity in Maiduguri, potentially attributable to irrigation and human activity. The study notes the public health implications of extreme dryness and recommends integration of humidity thresholds into NiMet meningitis early warning protocols for Borno State. Keywords: relative humidity, Maiduguri, harmattan, meningitis, semi-arid.