Monsoon misses June 1 date with Kerala, likely to arrive in 2-3 days

The much-awaited southwest monsoon has missed its normal June 1 onset date with Kerala and is now likely to arrive on the Indian mainland in the next two to three days, according to the India Meteorological Department (IMD).

The weather office said the Northern Limit of Monsoon has remained unchanged over the past couple of days. However, conditions are favourable for its further advance into parts of the southwest and southeast Arabian Sea, Lakshadweep, Kerala, Tamil Nadu, and more areas of the Bay of Bengal during the next two to three days.

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The weather office had on May 15 forecast an early onset over Kerala around May 26, with a model error margin of ±4 days.

Experts say the IMD uses specific criteria to declare the onset of the monsoon over Kerala.

Around 60 per cent of 15 designated weather stations across Kerala, Lakshadweep and coastal Karnataka must record at least 2.5 mm of rainfall for two consecutive days.

In addition, westerly winds must strengthen to 15-20 knots and extend up to about 12,000 feet, while satellite observations must show Outgoing Longwave Radiation (OLR) below 200 Watts per square metre, indicating deep convective clouding.

The monsoon is declared a day after the conditions are met simultaneously.

However, the criteria are yet to be satisfied. The required combination of rainfall, wind and cloud conditions is expected to be achieved around June 2 or 3, when the onset may be officially declared.

The southwest monsoon normally reaches Kerala on June 1, but the date is not exactly set in stone, it can vary. The seasonal rains arrived early in the previous two years, making landfall on May 31 in 2024 and May 27 in 2025.

Meanwhile, the IMD has forecast isolated heavy rainfall and thunderstorms over northeast and south Peninsular India during the week.

Moderate to severe thunderstorms, accompanied by squally winds of up to 70 kmph and isolated hailstorms, are likely over northwest, central and adjoining east India. But the relatively comfortable weather currently experienced in the northwest may change as day temperatures are expected to rise gradually by 4-6 degrees Celsius across many parts.

The June-September monsoon season is crucial for India as it provides more than 70 per cent of the country’s annual rainfall and is vital for agriculture, water resources and the broader economy. For 2026, however, the IMD has projected below-normal seasonal rainfall at 90 per cent of the Long Period Average (LPA), with a model error margin of ±4 per cent.

The LPA, based on data from 1971-2020, is 87 cm.

According to the forecast, below-normal rainfall is likely over most parts of the country, except some areas of northwest and northeast India, eastern parts of the south peninsula, adjoining east-central India and isolated pockets of east India, where normal to above-normal rainfall is expected.

Rainfall is likely to remain below normal over central, northwest and south peninsular India, as well as the Monsoon Core Zone, which comprises most of the country’s rain-fed agricultural regions. Northeast India is expected to receive normal rainfall.

According to the weather office, neutral El Niño-Southern Oscillation (ENSO) conditions are transitioning towards El Niño conditions over the equatorial Pacific, with climate models indicating a likely development during the season. Neutral Indian Ocean Dipole (IOD) conditions are expected to continue through the four-month season.