Air pollution has become a growing concern, especially in urban cities with rapidly developing economies, increasing infrastructure and vehicular population, and reduced green spaces. Fossil fuel and transportation are the main source of pollutive particles (e.g., sulfur oxide and nitrous) released into the atmosphere. Once they have entered the atmosphere, these particles create health problems, degrade air quality, and cause acid rain. Seasonal investigations on rainwater chemistry and particulate matter pollution (SPM, PM10, and PM2.5) were conducted to understand the recent state of the ambient air quality in Jakarta, Indonesia. The characteristics of PM2.5 were also analyzed during Ied Al Fitr in 2016 and 2017. Based on the observational data, the ambient air quality in Jakarta improved during the period of our study (2000–2016). The chemical constituents, i.e., the anion and cation concentrations, in precipitation show decreasing trends starting from 2006. Moreover, the PM10 and SPM concentrations also decreased slightly. The causes of these favorable trends are climatic conditions—namely, an increasing trend of rainfall—and policy intervention. Additionally, an assessment during the feast of Ied Al Fitr in 2016 and 2017 indicated a further decrease in PM2.5 due to highly reduced inner-city traffic. These events exhibited an extreme reduction of the PM2.5 concentration in Jakarta.