IMD Misses Rare Forecast Window as Monsoon Stalls

NEW DELHI — In a rare miscalculation that breaks a decade-long streak of precision, the India Meteorological Department (IMD) on Tuesday officially pushed back its arrival date for the southwest monsoon, admitting the crucial weather system will likely miss its previously predicted window and make landfall in Kerala around Thursday, June 4.

The delay comes as an unwelcome surprise. Back on May 15, weather officials confidently called for an early May 26 arrival. Even allowing for the standard four-day model error, the new June 4 timeline overshoots the absolute latest expected date of May 30.

This marks the first time since 2015 that the IMD’s custom operational forecast model has missed the mark on the monsoon’s mainland debut. Between 2005 and 2025, the department’s predictions had failed only once.

The Final Push: What’s Holding It Up?

According to IMD officials, the monsoon hasn’t lost its punch—it has simply stalled. The “northern limit” of the monsoon—essentially the front line of the massive cloud system—remains hovering just short of the Indian mainland.

However, a meteorological rescue is on the way. An upper-air cyclonic circulation brewing off the south Kerala coast is expected to provide the necessary atmospheric shove to drag the rain clouds ashore. Consequently, the IMD has hoisted heavy to very heavy rainfall warnings for Kerala over the next six to seven days.

Inside the Weather Bureau: Officials told reporters that conditions are finally turning “favourable” for the monsoon to advance into the southeast Arabian Sea, parts of Kerala, Tamil Nadu, and the Bay of Bengal by June 4.

Anatomy of an ‘Onset’

The IMD doesn’t just declare the monsoon’s arrival because of a heavy downpour; it follows a strict, scientific checklist. For the onset to be officially called, three distinct conditions must be met concurrently after May 10:

• The Rain Gauge Test: At least 60% of 14 designated weather stations across Kerala and neighboring coasts (including Kochi, Thiruvananthapuram, Kozhikode, and Mangaluru) must register 2.5 mm or more of rain for two consecutive days.
• The Wind Factor: Strong westerly winds must stretch deep into the atmosphere, up to roughly 4.5 km over the southeast Arabian Sea.
• The Cloud Cover: Outgoing long-wave radiation must plunge below 200 Watts per square meter, a satellite metric proving the presence of the deep, dense cloud decks characteristic of a true monsoon rather than passing summer showers.

High Stakes for the Agrarian Economy

The delay adds a layer of anxiety to an already tense agricultural outlook. This year’s monsoon is already projected to be “below normal” at just 90% of the long-period average, heavily suppressed by a strengthening El Niño phenomenon in the Pacific. With Indian agriculture profoundly reliant on these summer rains, scientists and farmers alike will be watching the skies this Thursday to see if the monsoon finally keeps its revised date.