Kerala is a narrow strip between the Arabian Sea and the Western Ghats, and the gateway through which India's southwest monsoon first arrives every year. It is also one of only a few Indian states to receive a second, distinct rainy season — the northeast monsoon — giving it one of the country's longest and most reliable combined rainy seasons. For live interactive rainfall, wind and satellite maps over Kerala, open VayuMet.
From west to east, Kerala rises in three bands: a low coastal strip laced with brackish backwaters (the largest being Vembanad Lake), a midland belt of hills and plantations, and the high Western Ghats (Idukki, Wayanad, the Anamalai and Cardamom hills) reaching over 2,000 m. The Palakkad Gap — the only major low-elevation break in the entire Western Ghats — lets drier air through to interior Tamil Nadu and gives that district a distinct rain shadow.
Winter (December-February) is mild and mostly dry. Pre-monsoon summer (March-May) brings heat and scattered thundershowers locally called 'mango showers'. The southwest monsoon (June-September) makes its first Indian landfall here, normally around 1 June, and drenches the windward Ghats. The northeast monsoon (October-December) then brings a second, smaller but still substantial rainy season — a combination unique to Kerala and Tamil Nadu among Indian states.
IMD uses a fixed set of criteria (rainfall at a network of Kerala stations, wind field strengthening, outgoing longwave radiation) to formally declare the monsoon's onset over Kerala each year, normally around 1 June with several days of year-to-year variability. This date effectively marks the start of the monsoon for the whole country.
Kerala's monsoon is not continuous rain — it alternates between 'active' spells of widespread heavy rain (often linked to an offshore trough or vortex in the Arabian Sea) and 'break' spells of much lighter rain, sometimes lasting a week or more.
As the southwest monsoon withdraws, northeasterly winds bring a second rainy season fed by the Bay of Bengal, contributing a meaningful share of Kerala's annual total, particularly in the south of the state.
Direct cyclone impact on Kerala is uncommon, but Cyclone Ockhi (2017) caused severe damage and loss of life along the south Kerala coast, showing the coast is not fully immune to Arabian Sea systems.
Frequencies cited from published IMD/IITM climatology where a source is named inline; day-count figures in the table below are computed directly from the 1951–2025 IMD daily archive.
The table below is a state-wide average across Kerala's 14 districts, built from IMD's real 1991-2020 gridded rainfall/temperature normals and 1951-2025 daily archives (not a forecast). The high-elevation Ghats districts (Idukki, Wayanad) receive far more rain than this average and the low coastal districts somewhat less — use the district climatology tool linked below for any single district's own figures.
| Season | Rainfall (mm) | Rain days | Mean Max / Min (°C) | Typical Hottest / Coldest (°C) | Sky (Sunny·Partly·Overcast days) |
|---|---|---|---|---|---|
| Winter Jan–Feb | 29.8 | 6.8 | 30.8 / 21.1 | 31.9 / 20.2 | 10.8·47.5·0.7 |
| Pre-Monsoon (Summer) Mar–May | 346.9 | 48.6 | 32.4 / 23.8 | 33.2 / 22.2 | 6.1·79.1·6.8 |
| Monsoon (SW) Jun–Sep | 1613.3 | 108.5 | 29.1 / 22.6 | 31.2 / 22.1 | 0.0·50.3·71.7 |
| Post-Monsoon Oct–Dec | 512.7 | 51.0 | 29.8 / 21.9 | 30.3 / 20.3 | 4.2·78.5·9.3 |
State figures are a simple average across 14 member districts (IMD Pune 1991–2020 normal; day-count and sky figures from real 1951–2025 daily archives — see District Climatology tool for any single district's own numbers, which can differ substantially from this state average).
Computed directly from the real IMD 1951–2025 daily gridded archive — not a forecast, and not the same as a single-station record. IMD's gridded temperature is 1°×1° (~111 km/cell) and rainfall is 0.25°×0.25° (~25 km/cell); both are spatial analyses of many station observations; a famous single-station record (e.g. a specific town's all-time hottest day) will typically read higher than the grid-cell value shown here, since one station reading isn't smoothed over a ~25–111 km box. "Place" is the nearest district to the grid cell where the extreme occurred, not necessarily the exact spot.
Monsoon (Jun-Sep). The 2018 and 2019 floods, driven by exceptionally heavy monsoon spells and reservoir releases, affected the Periyar, Pamba and Chalakudy river basins severely, particularly Idukki and the central Kerala lowlands.
Monsoon (Jun-Sep). Saturated, steep Western Ghats slopes in Wayanad and Idukki are highly landslide-prone during sustained heavy rain.
Post-monsoon / pre-monsoon. Kerala's coast faces chronic erosion and occasional direct cyclone impact, as in Cyclone Ockhi (2017).
Pre-monsoon & monsoon. Kerala has one of India's higher lightning-strike densities, a recurring cause of casualties in the pre-monsoon thunderstorm season.
Click a district on the District Climatology tool or search it on the 10-day forecast page for its own normals — the grid below is the full current list (India's Local Government Directory codes, cross-checked against the latest state reorganisation).