The India Meteorological Department (IMD) has not yet declared the official onset of the southwest monsoon over Kerala, even as large parts of the country wait anxiously for relief from intense summer heat. While the agency has indicated that the monsoon is likely to arrive within the next few days, the delay has prompted questions about what is holding it back and whether it could affect rainfall across India during the crucial June–September season.
Why Kerala Matters
Kerala serves as the gateway for the southwest monsoon into the Indian mainland. The date of its arrival is closely monitored because it sets the tone for the monsoon’s progress across the country. The normal onset date over Kerala is around May 26, but this year the expected arrival has shifted to between June 5 and June 10, reflecting slower-than-usual atmospheric developments.
When Is the Monsoon Expected to Arrive in Kerala This Year?
According to current forecasts, the monsoon is expected to reach Kerala between June 5 and June 10. However, the IMD follows a stringent scientific process before officially declaring the onset.
The declaration is not based on rainfall alone. The IMD requires three key meteorological conditions to be met simultaneously.
· First, at least 60 per cent of 14 designated monitoring stations across Kerala must record 2.5 mm or more rainfall for two consecutive days.
· Second, the monsoon wind field must be sufficiently established, with westerly winds extending up to the 600 hPa level and zonal wind speeds reaching 15–20 knots at the 925 hPa level.
· Third, Outgoing Longwave Radiation (OLR) values over a specified Arabian Sea region must fall below 200 Wm⁻², indicating the presence of deep cloud cover and active convection necessary for sustained monsoon activity.
Although parts of Kerala have witnessed intermittent showers in recent days, these atmospheric parameters have not yet aligned fully, preventing the IMD from making an official onset declaration.
Why Is the Monsoon Delayed This Year?
· Weak Monsoon Winds
One of the primary reasons for the delay is the weakness of moisture-bearing westerly winds over the Arabian Sea. These winds have not attained the required depth of 600 hPa, nor have they consistently reached the prescribed speed threshold of 15–20 knots. Without strong winds, moisture transport towards the Indian mainland remains limited.
· Incomplete Meteorological Conditions
The Indian Ocean, often described as the monsoon’s engine room, has not generated the level of convection needed for a vigorous onset. Outgoing Longwave Radiation values remain above the required threshold, indicating insufficient cloud formation and weaker thunderstorm activity.
· Emerging El Nino Influence
A developing El Nino event in the Pacific Ocean is also contributing to the delay. El Nino alters global atmospheric circulation patterns, often weakening monsoon winds and reducing moisture availability over India. Historically, several major drought years, including 2002 and 2009, have coincided with strong El Niño conditions.
Will the Delayed Monsoon Affect Rainfall Across India?
The concern extends beyond the onset date. The IMD’s long-range forecast for 2026 projects seasonal rainfall at 92% of the Long Period Average (LPA), placing it in the below-normal category. The LPA stands at 87 cm for the 1971–2020 period.
A weaker monsoon could have far-reaching implications. Agriculture may face lower yields in crops such as rice, cotton and soybeans due to reduced soil moisture. Given that agriculture supports nearly half of India’s population and contributes significantly to the national economy, rainfall deficits can have broader economic consequences. Hydropower generation could also be affected, adding pressure to energy resources.
Delayed Arrival, Broader Implications
While the southwest monsoon is still expected to reach Kerala within days, its delayed onset reflects deeper atmospheric challenges, including weak winds, incomplete monsoon conditions and the growing influence of El Nino. A delayed arrival does not automatically mean a poor season, but forecasts indicating below-normal rainfall warrant close monitoring. For a country where agriculture, water security and economic stability remain closely tied to monsoon performance, the coming weeks will be critical in determining whether the rains can regain momentum and deliver the relief India needs.
(With agency inputs)
