Late monsoon onset is a critical climatic stressor for agriculture in south Bengal, West Bengal, India, where the timing and distribution of rainfall strongly shape crop calendars, especially for Aman paddy and other kharif crops. This article examines the pathways through which delayed monsoon reduces agricultural productivity in the region. Using a qualitative review and analytical synthesis of meteorological, agronomic, and socio-economic sources, the paper shows that rainfall delay lowers productivity by delaying sowing, increasing irrigation dependence, compressing the crop-growth period, raising production costs, and increasing exposure to dry spells or waterlogging. Evidence from West Bengal indicates substantial rainfall variability over time, with IMD-based and journal-based studies documenting significant trends in seasonal rainfall, including June rainfall decline and changing monsoon structure (India Meteorological Department, 2025; MAUSAM, 2025). District-level studies further show that rain fed rice productivity in West Bengal is highly sensitive to dry spells, rainy-season onset, and water-balance conditions (MAUSAM, 2017). More recent studies reveal that agricultural productivity can be strongly affected by delayed monsoon onset and irregular rainfall even in relatively high-rainfall districts such as Cooch Behar and Bankura (Basak, 2026; DOAJ, 2025). Field-level reporting from south Bengal confirms that farmers experience delayed sowing, high pumping costs, and severe crop losses during deficient monsoon years (Down to Earth, 2022). The paper argues that late monsoon is best understood as a timing-and-variability problem rather than a simple rainfall-deficit problem and concludes with policy implications for irrigation, crop diversification, seasonal advisories, and climate adaptation.

Keywords: late monsoon, agricultural productivity, south Bengal, West Bengal, Aman paddy, rainfall variability, climate vulnerability, crop calendar