The study examined urban effects on precipitation amount and rainwater quality in Warri metropolis, Nigeria. The data used for this study were generated from field measurement of rainfall amount and quality and PM10 for one year period. A total of 34 rain gauges and High-Volume (HV) PM10 samplers, and 18 satirized containers were used to generate data on the amount of rainfall, PM10 and rainwater quality respectively. The HV PM10 was used to draw a known volume of ambient air through a size-selective inlet and through one or more filters from where the PM10 size range was collected on the filter for 24 hours. The rainwater samples were analyzed with the best probable methods. ANOVA, H- test, U- test and simple regression analysis were used to analyze the data. The results showed that rainfall in the urban area is 18% higher than the rural areas, and varied significantly (20%) within the urban areas. PM10 in the urban area is 150% and 90% above those of the rural area and WHO threshold, and such has strong implication on human health. Rainwater quality was generally lower in the urban canopy than in the countryside. Based on these enforcement of urban management laws is recommended.