Like flood year 2018, Kerala's monsoon to arrive early – Should we be concerned?

The southwest monsoon is expected to reach Kerala by May 27, ahead of its usual onset date of June 1, according to the India Meteorological Department (IMD). If the forecast holds, this would be the earliest monsoon onset over the Indian mainland since 2009, when it arrived on May 23.

The monsoon’s arrival over Kerala officially signals the start of the rainy season in India. It typically progresses across the country by July 8 and begins to withdraw from the northwest around September 17, fully retreating by October 15.

Past early monsoons and flood years raise concerns

Although the IMD maintains that there is no direct relationship between an early onset and the total rainfall during the season, the early arrival has drawn attention due to its timing in past years when severe floods occurred.

Major floods in 2007, 2009, 2014 and 2018 caused extensive damage across Kerala and other parts of the country. In 2018, for example, the monsoon reached Kerala on May 29 and led to devastating floods that affected 5.4 million people. Over 2 million were displaced, more than 400 lives were lost, and 341 landslides were reported across the state due to continuous, intense rainfall.

Above-normal rainfall expected this year

The IMD has forecast above-normal rainfall for the June–September 2025 season, ruling out El Niño conditions that typically suppress rainfall. Rainfall this year is projected to be 105% of the long-period average of 87 cm, with a model error of 5%.

According to classification, rainfall between 105% and 110% of the long-term average is considered ‘above normal’. Any figure beyond 110% is termed ‘excess’.

Impact on agriculture and water resources

The monsoon is vital for India’s agricultural sector, which supports over 42% of the population and contributes 18.2% to the GDP. It is also essential for refilling reservoirs used for drinking water and power generation.