Indian monsoon: Quick Facts

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Photos

Map showing the average date of onset of the summer monsoon across Asia.

Two world maps compare the Indian monsoon's climatic heat sources and sinks. The top map, labeled Summer Monsoon, highlights the monsoon trough over South Asia as a major heat source and the Mascarene High over the southwest Indian Ocean as a heat sink, with arrows indicating surface air flow from the ocean toward the continent. The bottom map, labeled Winter Monsoon, shows the Siberian High over northern Asia as a heat sink and the Maritime Continent region as a heat source, with air flow arrow

Map showing the withdrawal of the Indian monsoon, with orange lines and dates indicating the typical retreat timeline from northwestern India and Pakistan in early September, gradually moving southeast across the Indian subcontinent and reaching Sri Lanka by January 1. Surrounding countries and major water bodies such as the Arabian Sea and Bay of Bengal are labeled.

Workers transplanting rice near Mangalore, Karnataka, India. Agriculture on the Indian subcontinent frequently depends on summer monsoon rainfall because precipitation during other seasons may be sparse.

Graph depicting the influence of El Niño/Southern Oscillation (ENSO) on rainfall produced by the Indian summer monsoon. During years when ENSO is active, monsoon-driven precipitation over India often declines.

Graph of monsoon rainfall in India, 1871–1981. Annual rainfall amounts are depicted as percentages departing from the 110-year average. The red line superimposed on the graph suggests a recurring trend over this time period.

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