The spatial and temporal variability of tropical rainfall is a major governing factor of agrarian-based economic stability in developing countries like Sri Lanka. Temporal variability is shown in four major rainfall seasons, and spatial variability is shown in four major climatic zones in Sri Lanka. Cropping systems, water resources management, recharge of aquifers, surface water management, natural disasters and risk management mainly depend on the rainfall. The aim of the study is to visualize the spatiotemporal variability and trend analysis of rainfall in Sri Lanka. Meteorological rainfall point data were interpolated and derived the spatial annual rainfall distribution district polygon map. Ratnapura and Kalutara districts recorded the highest average annual rainfall, with values of 2891.78 mm and 2868.70 mm, respectively, while the lowest average annual rainfall was recorded in Hambantota district at 1565.60 mm during the period from 1997 to 2022. Mann Kendall non-parametric statistical test shows a positive trend of rainfall for Sri Lanka, and the Hambanthota district shows a negative trend of rainfall for the last 26 years. The wet zone shows a 25.38 mm/year increment of rainfall, the dry zone shows a 14.45 mm/year increment, the intermediate zone 17.48 mm/year increment and the arid zone 5.2 mm/year decrement according to the Sen’s slope.