India’s southwest monsoon, one of the country’s most closely watched weather events, is taking its time this year. Fresh weather model assessments from the India Meteorological Department (IMD) suggest that the strong upper-level winds needed to support a full-fledged monsoon over South India may develop only after June 5-6. While several parts of Kerala have already witnessed rain, yet the complete set of conditions required for an official declaration has not yet come together.Kerala Has Rain, But Monsoon Conditions Are Still BuildingRain-bearing clouds have already reached parts of Kerala, bringing pre-monsoon showers and raising expectations of an early arrival. However, the IMD says rainfall alone does not mark the beginning of the southwest monsoon. The larger atmospheric system responsible for the monsoon is still taking shape. Because of this, the season may begin gently before gaining strength over the following days.The IMD had earlier expected the monsoon to reach Kerala around May 26. Changes in weather patterns, however, slowed the development of the atmospheric features needed for an official onset declaration.Why the Monsoon Matters So MuchThe southwest monsoon is often seen as the backbone of India's economy. From June to September, it delivers more than 70% of the country's annual rainfall.The rains help farmers begin sowing operations, refill reservoirs, improve groundwater reserves and provide relief from intense summer temperatures. A timely monsoon also supports drinking water supplies, irrigation systems and power generation across many regions.What Exactly Is the Onset of Monsoon?The onset of the southwest monsoon over Kerala marks the official start of India's four-month rainy season.It is more than just the arrival of rain. The onset reflects a major shift in atmospheric and oceanic circulation across the Indo-Pacific region. Because of its importance, the IMD follows a scientific process before announcing that the monsoon has officially arrived.Even when rain falls in some areas, the declaration is not made until all required conditions are met at the same time.The Three Conditions IMD Checks Before Making the AnnouncementThe weather department follows criteria adopted in 2016. These guidelines focus on rainfall, wind patterns and cloud activity.1. Rainfall Must Be WidespreadAt least 60% of 14 selected weather stations across Kerala and Lakshadweep must record 2.5 mm or more rainfall.The rainfall must continue for two consecutive days after May 10. If the other conditions are also satisfied, the IMD declares the onset on the second day.The stations include Minicoy, Amini, Thiruvananthapuram, Punalur, Kollam, Alappuzha, Kottayam, Kochi, Thrissur, Kozhikode, Thalassery, Kannur, Kasaragod and Mangaluru.2. Winds Must Be Strong EnoughThe monsoon depends heavily on moisture-laden westerly winds.For the onset declaration, these winds must extend up to the 600-hectopascal level in the atmosphere. Wind speeds are expected to remain in the range of 15-20 knots, or roughly 28-37 kmph, over parts of the Arabian Sea and nearby regions.These winds transport moisture from the Indian Ocean towards the Indian subcontinent, helping the monsoon advance.3. Cloud Activity Must Show a Strong SignalThe IMD also monitors Outgoing Longwave Radiation (OLR), a measure of heat escaping from the Earth into space.For monsoon onset, OLR values should fall below 200 watts per square metre over a designated area. Lower values usually indicate dense cloud cover and active weather systems, both of which are associated with a developing monsoon.The Waiting Game ContinuesFor now, India's most important weather season remains just short of an official arrival. The rain has started appearing in parts of Kerala, but the IMD is waiting for rainfall, wind conditions and cloud activity to align simultaneously.Once all three pieces fall into place, the weather department will declare the onset of the southwest monsoon over Kerala, setting in motion the gradual spread of rains across the rest of the country.