Study of the Relationship Between Rainfall and Atmospheric Pressure in Lagos State

The relationship between surface atmospheric pressure and rainfall onset is a fundamental meteorological phenomenon with practical importance for short-term weather prediction and agricultural planning. In Lagos State, South West Nigeria, the Inter-Tropical Convergence Zone drives seasonal rainfall patterns, and local pressure variations associated with convective activity modulate daily rainfall events. This study investigates the relationship between surface atmospheric pressure and rainfall occurrence in Lagos metropolis using one-year records of barometric pressure and daily rainfall from Murtala Muhammed International Airport meteorological station. Pressure data recorded at 3-hour intervals are analysed alongside rain gauge totals using correlation analysis and logistic regression modelling. Results indicate that surface pressure drops of 2 to 5 hPa occurring over 6-hour windows reliably precede convective rainfall events during the April to October rainy season. A predictive threshold of 1011 hPa identifies the pressure level below which rainfall probability exceeds 70 percent in the wet season. No significant pressure-rainfall relationship is found during the harmattan months. The study provides a basis for developing a low-cost barometric rainfall warning system for smallholder farmers and coastal fishers in Lagos State. Keywords: atmospheric pressure, rainfall, Lagos, meteorology, weather prediction