Mumbai has recorded one of its wettest starts to July in recent years, receiving almost an entire month’s rainfall within the first seven days. The intense downpour flooded roads, disrupted rail and road transport, and overwhelmed the city’s drainage network. According to India Meteorological Department (IMD), the Colaba observatory recorded 791 mm of rainfall between July 1 and 7, exceeding its July average of 768.5 mm. Santacruz recorded 879 mm, close to its monthly average of 919.9 mm.
What is El Niño?
El Niño is a naturally occurring climate phenomenon caused by unusually warm sea surface temperatures in the central and eastern Pacific Ocean. It is generally associated with weaker monsoons and delayed rainfall across India. This year, the southwest monsoon reached Mumbai nearly two weeks later than usual, consistent with an El Niño pattern. However, once it arrived, it brought exceptionally heavy rainfall instead of gradual showers.
Why did heavy rainfall occur during an El Niño year?
Meteorologists say there is no contradiction. While El Niño can influence the timing of the monsoon, climate change is increasingly affecting how it rains. Warmer air and oceans can hold more moisture. As global temperatures rise, this excess moisture is released in short, high-intensity bursts, resulting in cloudbursts and extreme rainfall rather than prolonged, moderate showers.
As per officials, although El Niño years generally have fewer rainy days, rainfall is now increasingly concentrated into short, intense spells because of global warming.
Why was this week’s rain so intense?
Experts say multiple weather systems combined to trigger the downpour. According to climate scientists, warming over West Asia altered wind patterns over the Arabian Sea, increasing moisture levels. At the same time, a low-pressure system over the Bay of Bengal supplied additional moisture. As these moisture-laden winds reached the Western Ghats, they were forced upwards, producing exceptionally heavy rainfall over Mumbai.
Rainfall intensity begins to ease
After several days of relentless rain, conditions have started to improve. In the 24 hours ending Tuesday morning, Santacruz recorded 94 mm of rainfall while Colaba received 90 mm, marking the first time in five days that both observatories recorded less than 100 mm. While the IMD has kept Alerts in place, lighter showers are expected over the next few days, offering Mumbai some relief after an exceptionally wet start to July.
