Monsoon arrives in Maharashtra, earliest in 35 years

Having now entered Maharashtra, Shubhangi Bhute, director of IMD Mumbai said that Mumbai could see the advancement of southwest monsoon over the next three days, making it perhaps the city’s earliest date of monsoon onset ever recorded. Prior to this, the earliest onset of monsoon in Mumbai has been logged on May 29 — in the years 1971, 1962 and 1956.

On Saturday, IMD declared the onset of southwest monsoon in Kerala. A day after, southwest monsoon further advanced in west central and east central Arabian Sea, as well as covered entire Goa, crossed parts of Karnataka besides entering Maharashtra. In the north-eastern region, monsoon entered into parts of Mizoram, Manipur and Nagaland on Sunday.

The arrival of the monsoon in Maharashtra on Sunday makes it the earliest onset ever recorded in the state in the past 35 years.

Prior to this, the earliest onset was observed in the year 1990, when monsoon set into the state on May 20. This is a stark departure from its typical date of monsoon onset of June 5. Data from the MeT shows that with June being the typical date of onset in Maharashtra, monsoon has arrived in the state as early as May only in six years over the past six decades.

Shubhangi Bhute, director of IMD Mumbai said, “The conditions have been very favourable for the early onset of monsoon in Kerala, and early progression in Maharashtra. Furthermore, the conditions were satisfying all the parameters and criteria on the basis of which onset is declared.”

For the record, the onset of monsoon over Kerala is determined on the basis of parameters such as adequate rainfall over at least 60 per cent of the 14 earmarked stations, wind field, outgoing longwave radiation (OLR) and northern limit of monsoon (NLM).

Alluding to the early onset of monsoon in Mumbai over the next three days, the IMD on Sunday added, “Conditions are favourable for further advance of Southwest Monsoon into some more parts of central Arabian Sea, some more parts of Maharashtra including Mumbai, Karnataka, some parts of Andhra Pradesh, remaining parts of Tamil Nadu, some more parts of west central & north Bay of Bengal and some more parts of Northeastern states during next 3 days.”

The typical date of monsoon onset in Mumbai is June 11. In the past two decades, the earliest monsoon onset in Mumbai was observed in 2006 when the southwest monsoon had advanced on May 31. Besides this, the earliest date of onset ever recorded in Mumbai stands at May 29, which was recorded in the years 1971, 1962 and 1956.

The early onset has come at a time when Mumbai is already reeling under a surplus of over 700 percent from the actual normal rain for the month of May. Making it the city’s wettest May since 2021, the Colaba coastal observatory has recorded 159 mm rain while the Santacruz station has recorded 164 mm rain.

With the projection of early onset of monsoon, Mumbai can also shatter its 2021 record, when the city received 256 mm rain, in what could make it the city’s rainiest May in the past two decades. The city’s record for the wettest May was clocked in the year 2000, when 388 mm rain lashed Mumbai’s Santacruz division.

Not only the metropolis but the entire state of Maharashtra is currently experiencing an unusual May with Buldhana district having logged a surplus of over 4,000 percent from its actual long period average for the region, while coastal districts like Sindhudurg and Raigad have recorded surplus of over 2,600 percent and 2,000 percent respectively so far.

Amid the likelihood of early onset, the IMD has placed Mumbai and its neighbouring districts of Thane, Palghar under a yellow alert stating the likelihood of heavy rainfall until at least May 28.