<p>The stability of hill slopes is a critical concern in regions prone to landslides, affecting both human, nature and infrastructure. In tropical countries like Bangladesh, many soil slopes consist partially or entirely of unsaturated soils, where suction forces enhance the shear strength of slope materials. Rainfall precipitation leads to water infiltration into the soil, increasing its moisture content and diminishing suction forces, potentially resulting in slope failure. Conversely, hydraulic conductivity significantly affects slope stability and is particularly reliant on the soil–water characteristic curve of the slope materials. This paper examines the influence of hydraulic conductivity and rainfall infiltration on the stability of a hill slope situated in the Chattogram Metropolitan City region. Laboratory and field studies, coupled with numerical analysis were conducted for both steady-state and transient seepage condition across the year to simulate the rainfall infiltration through unsaturated soils. The study revealed that short-term, low-intensity rainfall results in a reduction of Factor of Safety (FoS) toward the end of each month. In contrast, long-term, high-intensity rainfall leads to a decrease in FoS until the middle of the month, followed by a subsequent increase until the end of each month. However, the FoS increases in the dry season when rainfall infiltration is less than hydraulic conductivity, whereas it decreases in the rainy season when rainfall infiltration is higher than hydraulic conductivity. The suction strength at the top of slope diminishes by 60% following rainfall.</p>