Published on: July 10, 2025 6:54 pm
India’s monsoon season isn’t just about rain—it’s about survival, economy, and national planning. And every year, the Indian Meteorological Department (IMD) declares the onset of monsoon in Kerala as the official start of the southwest monsoon in India. But why Kerala? Why not Tamil Nadu, Goa, or Maharashtra?
Let’s dive deep into the scientific, geographic, economic, and strategic reasons behind this consistent weather practice—and why it matters to 1.4 billion people.
📍 The Science Behind Monsoon Onset in Kerala
🌬️ Southwest Monsoon Winds and Arabian Sea Branch
The southwest monsoon winds, originating from the Indian Ocean, gain moisture while traveling over the Arabian Sea. Kerala, located on the southwestern coast of India, is the first landmass these winds encounter.
Kerala becomes the first state to receive the full force of monsoon winds, making it the ideal observational point.
🧪 IMD’s Scientific Parameters for Declaring Monsoon
The India Meteorological Department (IMD) uses a standard scientific formula to declare monsoon onset over Kerala:
- 10+ mm rainfall for two consecutive days at least in 60% of selected weather stations (e.g., Thiruvananthapuram, Alappuzha, and Kozhikode)
- Consistent wind pattern reversal at 850 hPa pressure level
- Outgoing Longwave Radiation (OLR) below 200 W/m² over the area
This data-driven model ensures a reliable, repeatable benchmark for forecasting.
🌍 Why Not Other States?
🚫 Tamil Nadu – Receives North-East Monsoon
Despite being a coastal state, Tamil Nadu is not influenced by the southwest monsoon. It receives most of its rainfall during the north-east monsoon (October–December).
🚫 Goa, Maharashtra – Monsoon Reaches Later
These states receive rains after Kerala. Monsoon winds take time to travel northward. The pattern is progressive, and declaring monsoon in any of these would cause timing inconsistencies.
🧭 Geographic Significance of Kerala in Monsoon Monitoring
🏞️ Western Ghats – The Rain Trigger
Kerala is bordered by the Western Ghats, which play a crucial role in orographic rainfall—when moist winds rise along mountains and cool down to form rainclouds.
This makes Kerala a natural rain gauge and the perfect scientific test zone for monsoon behavior.
🌐 Gateway to the Indian Subcontinent
Kerala acts as the climatic gateway for monsoon to enter India. Once it hits Kerala, the monsoon spreads like a green wave across the Indian subcontinent.
🌾 Agricultural & Economic Importance
🌱 60% of Indian Agriculture is Rain-Fed
More than 60% of India’s farmland depends on monsoon rains, especially in states like Uttar Pradesh, Madhya Pradesh, Maharashtra, and Bihar. Knowing when the monsoon begins helps farmers:
- Prepare fields for sowing
- Plan irrigation and fertilization cycles
- Time harvests more accurately
💰 Monsoon Impacts the Economy
From inflation rates to GDP growth, the monsoon plays a central role in India’s economy:
- Good monsoon = Lower food prices, more exports, economic stability
- Poor monsoon = Crop failure, food inflation, rural distress
👉 Related Read: How AVOD is Changing India’s Economy
📰 Role of IMD and Government Agencies
🛰️ Real-Time Monitoring from Satellites
IMD uses data from satellites like INSAT-3D/3DR, SCATSAT, and Megha-Tropiques to monitor:
- Cloud patterns
- Sea surface temperature
- Wind vectors and jet streams
🛠️ Forecasting Models and Monsoon Bulletins
The Monsoon Mission by the Indian government combines:
- Numerical weather prediction (NWP)
- Dynamical models from NOAA, ECMWF
- Indigenous models like MOM (Modular Ocean Model)
Daily bulletins help policymakers, farmers, and disaster response teams prepare accordingly.
🗓️ How Monsoon Progresses After Kerala
🧭 Typical Monsoon Timeline Across India
| Date | Region |
|---|---|
| ~June 1 | Kerala |
| ~June 10 | Karnataka, Konkan |
| ~June 15 | Maharashtra, Telangana |
| ~June 20 | Madhya Pradesh, Gujarat |
| ~June 25 | Delhi, East UP |
| ~July 1–10 | Punjab, Bihar, North India |
📉 Tracking Delays and Deficits
IMD also issues alerts for delayed onset or rainfall deficit areas, impacting crop sowing cycles and water reservoir planning.
🔍 Why Kerala’s Monsoon Matters for the Nation
🇮🇳 National Level Planning Starts with Monsoon
- Reservoir stocking for hydropower and drinking water
- Transport scheduling for agriculture and logistics
- Disaster preparedness in flood-prone zones
- Stock market trends—monsoon can affect stock prices of agri-based companies
🧠 Psychological & Cultural Impact
In Indian culture, the monsoon brings renewal, romance, and relief. Its arrival is celebrated in songs, literature, and festivals like:
- Ashadhi Ekadashi
- Sawan Month Vrat
- Onam (Kerala’s own monsoon festival)
🧾 Conclusion – A Rain That Shapes a Nation
Declaring the monsoon onset in Kerala is more than a weather event—it’s a national signal that impacts everything from farming and power to disaster planning and stock markets.
Tracking Kerala ensures a scientific, consistent, and actionable approach that benefits the whole country. As India continues to modernize its meteorological infrastructure, this small coastal state will remain the climatic gatekeeper for the world’s largest monsoon system.