Between late June and July 8, Mumbai recorded its wettest start to the monsoon since 2000, logging approximately 1,240 mm of total rainfall by July 6. The city experienced an extraordinary, record-breaking
deluge during the first week of July, effectively receiving an entire month’s worth of rain in just seven days. But how did Mumbaireceive record rainfall during an El Niño year?
MUMBAI RAINFALL IN 2026
The intense downpours shattered several local climatological averages and historical records:
Monthly Averages Surpassed
- Colaba Observatory recorded 791 mm of rainfall between July 1 and July 7, surpassing its normal July monthly average of 768.5 mm.
- Santacruz Observatory logged 879 mm during the same seven-day period, nearly matching its average July rainfall of 919.9 mm.
Historical Milestones
- South Mumbai witnessed its wettest July day in 50 years during this period.
- The five-day spell between July 2 and July 6 yielded more than 750 mm of rainfall, more than double the typical 350 mm average for that period.
- By July 6, the city had already recorded two days exceeding the India Meteorological Department (IMD) benchmark for “extremely heavy” rainfall of 204.5 mm.
- On July 5 alone, the rainfall grid recorded more than 225 mm of precipitation. The Santacruz Observatory also logged 268 mm in a single 24-hour period, marking its second-highest July 24-hour rainfall in 15 years.
- Mumbai’s seven-day rainfall total exceeded Delhi’s average annual rainfall and nearly matched Bengaluru’s annual average.
MUMBAI RAIN: WHAT ACTUALLY HAPPENED
The monsooninitially arrived in Mumbai nearly two weeks later than usual following a dry June. However, an active phase triggered by weather systems over the Arabian Sea and a persistent shear zone unleashed short, high-intensity bursts of rain at the turn of the month. Following the peak intensity, the IMD downgraded warnings to a Yellow Alert as rainfall eased to a moderate pace around July 8.
Climate change and record ocean temperatures are increasingly overriding the traditional drying influence of El Niño, fundamentally altering the behaviour of the Indian monsoon. While the strengthening El Niño delayed the arrival of the 2026 monsoon by nearly two weeks, once active weather systems developed, they triggered a relentless, record-breaking spell of rainfall across Mumbai.
Climate scientists from the India Meteorological Department (IMD) and leading research institutions attribute this apparent contradiction to several key factors:
Rapid warming of the Arabian Sea: The Arabian Sea is experiencing record-high sea surface temperatures. Warmer waters act as a vast energy reservoir, increasing evaporation and continuously supplying moisture to the atmosphere, allowing rain clouds to regenerate over coastal Maharashtra.
Dual-ocean system operating simultaneously: Active low-pressure systems over the Bay of Bengal shifted their tracks. Instead of moving northwest, they travelled westward across central India. As both the Arabian Sea and the Bay of Bengal supplied abundant moisture to the core monsoon region, the moisture converged over western India. The Western Ghats then forced this moisture-laden air upward, producing intense, concentrated rainfall over Mumbai.
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Global warming is changing the nature of the monsoon: Under a warming climate, El Niño may still reduce the total number of rainy days during the season. However, the atmosphere can hold about 7% more moisture for every 1°C increase in temperature. As a result, rainfall is increasingly released through short-duration, high-intensity cloudbursts. This allowed Mumbai to exceed its normal July monthly average of 768.5 mm within just the first seven days of the month. Experts warn that El Niño can no longer be studied in isolation from climate change, as the interaction between the two is creating increasingly unpredictable and dangerous urban flooding events.
WHAT IS EL NIÑO?
The 2026 El Niño is rapidly intensifying into a potentially historic “super” El Niño, with Pacific sea surface temperatures forecast to rise 2°C to 3°C above average. Developing against the backdrop of an already record-hot climate, it is increasing the risk of extreme weather, including drought across parts of Asia, flooding in the Americas, and record global temperatures.
El Niño is a natural climate phenomenon in which warmer-than-average waters spread from the western Pacific toward the eastern Pacific near South America. This shift alters atmospheric pressure patterns, affecting rainfall and temperatures around the world. The 2026 event is particularly significant because it is unfolding on a planet that is already experiencing record-high background temperatures.
India and Asia: Forecasters, including the India Meteorological Department, closely monitor El Ninobecause of its tendency to weaken the southwest monsoon. This year, delayed monsoon onset and below-normal seasonal rainfall remain concerns for agriculture and water resources.
The heat released from the Pacific Ocean into the atmosphere is expected to push 2026 and 2027 toward record-breaking global temperatures.
With agency inputs
