Air pollution remains one of the most critical environmental challenges in India, particularly in urban regions where rapid industrialization, population growth, and escalating energy demands have significantly deteriorated air quality. Addressing these challenges requires a deeper understanding of pollution trends and the factors driving them in urban areas. This study examines the spatiotemporal trends of key criteria air pollutants PM10, PM2.5, SO2, NOx, CO, and O3 and their association with climatic factors across four major Indian megacities: Delhi, Mumbai, Kolkata, and Chennai, using data from the Central Pollution Control Board (CPCB) and Indian Meteorological Department (IMD) for the years 2018 to 2022. Statistical techniques such as the Pearson correlation, Mann–Kendall trend analysis, and generalized extreme value (GEV) analysis were employed to evaluate pollutant variability and association with meteorology. Particulate matter dominates the pollution profile, with average concentrations of PM2.5 and PM10 reaching up to 108 and 215.1 µg/m3, respectively, while extreme events in Delhi recorded monthly maxima exceeding 344 and 536 µg/m3, respectively. Seasonal patterns indicate peak pollution during winters due to stable atmospheric conditions, whereas monsoons show significant reductions owing to wet deposition. Although pollutant levels are higher than the permissible standards in most cases, the overall pollution trend is declining in all other megacities except Mumbai, which has substantially higher concentrations, necessitating targeted interventions. Alongside ground-based observations, annual emission trends from the Emissions Database for Global Atmospheric Research (EDGAR) were used to assess inter-annual changes and regional distribution patterns of pollutants. Additionally, meteorological factors negatively correlate with pollutant levels, highlighting the importance of tailoring mitigation strategies to local climatology. This research offers critical insights for designing region-specific mitigation strategies to achieve sustainable air quality improvements.