Several parts of India, including the national capital Delhi, have witnessed rainfall over the past three days, leading many to believe that the southwest monsoon has arrived. However, the reality is quite different. This year's monsoon is running behind schedule and has not yet officially reached Kerala, the gateway for the monsoon into India.
Why is it raining if monsoon hasn't arrived?
India experienced intense heat throughout May, particularly in northern regions, which led to the formation of a "heat dome". The "heat dome" effect caused large amounts of water to evaporate from the Earth's surface. This moisture formed clouds that have brought rainfall to various parts of the country. While these showers have provided relief from the heat, they are not considered monsoon rains.
It is pertinent to mention that the southwest monsoon begins when moisture-laden westerly winds from the Arabian Sea move over the Indian subcontinent, bringing widespread rainfall. The rainy season typically lasts for about four months and begins with the monsoon's arrival in Kerala. About a month after reaching Kerala, the monsoon spreads across the entire nation, bringing heavy downpours to every region.
How does IMD declare onset of monsoon?
The India Meteorological Department (IMD) officially declares the onset of the monsoon only when three conditions are met simultaneously:
- Continuous rainfall at least 60% of designated weather stations in Kerala.
- Westerly winds over the Arabian Sea reaching a specified speed.
- Adequate cloud cover over the region.
At present, Kerala is receiving rainfall, and cloud cover is sufficient, but the westerly winds remain weaker than required. As a result, the IMD has not yet officially declared the onset of the monsoon.
Why has IMD revised date multiple times?
The Met department has initially forecast that the monsoon would reach Kerala by May 26. However, it later revised the expected date to May 28 and then to June 1. The latest forecast suggests that the monsoon is unlikely to arrive before June 3.
Many experts believe that further delays may still occur. However, a monsoon arrival in Kerala by June 8 is still considered within the normal range. Once it reaches Kerala, the monsoon gradually advances across the country and typically covers all of India by the first week of July.
Cyclone in Bay of Bengal affecting monsoon?
Due to a cyclone formed in the Bay of Bengal, rainfall has occurred in the eastern parts of the country and strong winds to states such as Uttar Pradesh and Rajasthan. However, as a result of this cyclone, the westerly winds are weakening further, contributing to the delay in the monsoon's advance, and the threat of El Niño is also mounting.
The IMD had earlier forecast seasonal rainfall at 92 per cent of the long-period average, but it has now revised the estimate downward to 90 per cent. Weather models suggest that the westerly winds may strengthen from June 1 onward, which could allow the monsoon to reach Kerala within the following few days.
El Niño effect
Meteorological agencies in India and abroad have warned of a high probability of an El Niño event developing later this year.
El Niño occurs when sea surface temperatures in the Pacific Ocean become warmer than normal. Such conditions often result in below-normal rainfall in India, particularly during August, September and November. Winter rainfall can also decline.
Forecasts suggest that El Niño conditions could emerge between September 2026 and February 2027.
Since a large portion of India's population depends on agriculture and more than half of Indian farmers rely on monsoon rainfall, any delay in the monsoon or strengthening of El Niño conditions is being closely watched as a potential concern for agriculture, water resources and the broader economy.
