Last week, Mumbai recorded an all-time high rainfall for the month of July (1,474 mm)—more than its 2014 record (1,468.5 mm). While the intense spell of rainfall was a welcome respite from the heat and humidity, climate scientists who have been tracking weather conditions for decades say that the city's haphazard rainfall pattern is a cause for concern.

Mumbai's weather conditions took a drastic turn at the beginning of the 21st century—a predictable outcome of the rapid industrialisation that the city was and is still undergoing. Intense spells of rainfall increased, with the major difference being that now these moderate to heavy spells occurred over a much shorter period of time—leading to lesser percolation of underground water. Krishnanand Hosalikar, Deputy Director-General of Meteorology with the Indian Met Department (IMD-Mumbai), who has over 25 years of service under his belt, recalls his childhood days. "There used to be more than 100 days of rainfall back then, with light to moderate showers occurring continuously over a span of three to four days. While there was intense rainfall, it is more widespread now. The reason for this change is urbanisation. Concretisation has changed the land use pattern of the city. This has increased the water runoff. Earlier, rainfall would seep into the ground, but now, because of concrete and paver blocks, it is going into the gutters. This has also caused strain on the city's nullahs."