The southwest monsoon, which regained momentum this week, is expected to cover most parts of northwest India, including Delhi, by June 25 well ahead of the usual dates, the India Meteorological Department (IMD) said, PTI reported.

The primary rain-bearing system reached Kerala on May 24, marking its earliest onset over the Indian mainland since 2009, when it arrived on May 23.

Aided by strong low-pressure systems over the Arabian Sea and the Bay of Bengal, the monsoon advanced quickly over the next few days, covering parts up to central Maharashtra, including Mumbai, and the entire northeast by May 29.

However, it stalled between May 28-29 and remained inactive until June 10-11, before becoming active again.

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The prolonged dry spell since early June led to a sharp rise in temperatures, triggering heatwave conditions across large parts of northwest and central India from June 8-9.

According to the IMD’s extended range forecast, the monsoon is now expected to cover the remaining parts of central and eastern India, along with some areas of northwest India, by June 18.

It is likely to advance over most parts of northwest India between June 19 and June 25.

“The system is likely to reach Delhi by June 22-23, ahead of the normal onset date of June 27,” an IMD official said.

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Meteorologists say the date of monsoon onset does not directly correlate with the total seasonal rainfall. An early or delayed arrival in Kerala or Mumbai does not necessarily indicate similar progress in other parts of the country.

They explain that the monsoon is influenced by a complex set of global, regional and local factors, and is often marked by significant variability.

In its May forecast, the IMD had said India is likely to receive 106 per cent of the long-period average rainfall of 87 cm during the June-September monsoon season.

Rainfall between 96 and 104 per cent of this 50-year average is considered “normal”.

Above-normal rainfall is expected in most parts of the country, except Ladakh, adjoining Himachal Pradesh, the northeast, and some parts of Bihar, Jharkhand, West Bengal and Odisha. Some isolated areas in Punjab, Haryana, Kerala and Tamil Nadu may record below-normal rainfall.

The monsoon remains critical for India’s agriculture sector, which supports the livelihood of nearly 42 per cent of the population and contributes around 18.2 per cent to the country’s GDP.

It also plays a key role in replenishing reservoirs, essential for drinking water supply and power generation.