New Delhi: The southwest monsoon has made an early entry into India this year, reaching Kerala on May 24—eight days ahead of its usual onset date of June 1. This is the earliest arrival of the monsoon since 2009 and aligns with the Indian Meteorological Department’s (IMD) prediction, which had forecast an onset around May 27, with a four-day margin.
According to the IMD, the official declaration of the monsoon’s arrival depends on several scientific indicators. These include rainfall of 2.5 mm or more in at least 60 percent of 14 designated weather stations across Kerala and nearby areas for two consecutive days, westerly winds blowing at 15–20 knots, and outgoing longwave radiation (OLR) levels below 200 W/m². This year, all these criteria were met, prompting the early declaration.
Global climate patterns
The early onset has already triggered heavy rainfall across several parts of Kerala. Historically, the onset dates of the monsoon in Kerala have shown wide variation. The earliest recorded arrival was on May 11, 1918, and the latest on June 18, 1972.
Two major global climate patterns—El Nino and La Nina—significantly influence the Indian monsoon. During El Nino years, ocean temperatures rise, often resulting in weaker monsoons. In contrast, La Nina leads to cooler ocean temperatures and usually brings enhanced rainfall. In 2023, India witnessed six percent less rainfall due to El Nino conditions. However, the IMD has ruled out any El Nino activity this year and expects La Nina to develop later in the season, boosting the likelihood of above-normal rainfall in 2025.
Early onset not enough
Meteorologists attribute this year’s early monsoon to higher-than-usual sea surface temperatures in both the Arabian Sea and the Bay of Bengal, which increased atmospheric moisture and strengthened monsoon winds. Cyclonic circulations and active western disturbances also contributed to the early onset. Additionally, the larger backdrop of global climate change is playing a growing role in shifting weather patterns.
However, experts caution that an early monsoon does not necessarily mean it will be prolonged or more intense. Rainfall distribution still depends on several dynamic weather factors, including ocean temperatures, air pressure systems, and global wind patterns. If the monsoon continues with steady momentum, India could see good rainfall, benefiting agriculture. Conversely, if it slows down, rainfall may fall short of expectations.
Nonetheless, early rains are already proving advantageous for farmers. Since intense summer heat has been largely absent in many areas, soil moisture levels remain intact, allowing early sowing. If rainfall continues regularly, crop yield is likely to improve significantly this year.
