How IMD Declares Monsoon Onset Over Kerala, Decoded

Monsoon onset over Kerala is a formal scientific call, not just heavy rain on a given day

IMD checks three things together: rainfall at 14 stations, wind depth and satellite heat (OLR)

60% of 14 stations must record 2.5mm+ rain for two straight days after May 10

Westerly winds must deepen to 600 hPa and OLR must drop below 200 W/m²

Onset over Kerala does NOT mean rain has reached your city — that comes later