How to read the charts
Each bar is one day's rain: IMD's 24-hour total ending 08:30 the next morning, so a bar belongs to the day the rain mostly fell. The four blue days run from three days before Ganesh Chaturthi to Chaturthi itself. A welcome wash is a year in which it rained on at least two of those four days, a rainy day being 2.5 mm or more, IMD's threshold.
Where the rain is measured
The average of four IMD 0.25° grid cells (19.0 and 19.25N × 72.75 and 73.0E) — a block of about 55 km by 50 km from Colaba in the south to Mira Road and Thane in the north, and from the sea east across Mulund and Navi Mumbai to Panvel. It covers the Santacruz and Colaba observatories. Gridded values are interpolated from surrounding gauges, so they smooth the single-gauge extremes that make headlines.
Sources
India Meteorological Department, Pune: 0.25° × 0.25° daily gridded rainfall over India, 1901–2025 (Pai et al. 2014, MAUSAM 65). Festival dates: Bhadrapada Shukla Chaturthi as observed in Mumbai, drikpanchang.com. 2026 is not shown — Chaturthi falls on 14 September 2026 and the record is still open.