Sikkim packs one of the steepest elevation ranges of any Indian state into a small area — from around 300 m in the south to Kangchenjunga's 8,586 m on the Nepal border — and sits at the intersection of monsoon-driven summer rainfall and Himalayan winter snowfall, alongside a well-documented and growing glacial lake outburst flood (GLOF) risk. For live interactive rainfall, wind and satellite maps over Sikkim, open VayuMet.
Sikkim rises extremely quickly from its low southern border with West Bengal to the high Himalaya along its northern and western borders with Tibet and Nepal, including Kangchenjunga, the world's third-highest peak. Its small area combined with this extreme relief means climate can change dramatically over short horizontal distances.
The monsoon (June-September) brings heavy rainfall to southern and lower Sikkim, decreasing with altitude and becoming markedly drier in the high north near the Tibetan plateau. Winter brings snowfall to higher elevations, driven by a combination of western disturbances and the Himalaya's own moisture. North Sikkim's high-altitude areas are considerably colder and drier year-round than the south.
Southern and lower Sikkim receive substantial monsoon rainfall, which drops off significantly toward the high, dry north near the Tibetan plateau.
Winter snowfall at higher elevations comes from a combination of western disturbances reaching this far east and locally generated Himalayan moisture.
Sikkim's high-Himalayan glacial lakes present a real and growing hazard; the October 2023 South Lhonak Lake outburst caused severe flooding down the Teesta river, including damage to hydropower infrastructure, and remains a major recent illustration of this risk.
Sikkim's very steep terrain makes it prone to landslides and highly localised extreme-rainfall cloudburst events during the monsoon.
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 Sikkim's 4 districts, built from IMD's real 1991-2020 gridded rainfall/temperature normals and 1951-2025 daily archives (not a forecast). Given Sikkim's extreme elevation range, individual locations can differ enormously from this average — 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 | 16.7 | 14.9 | 8.7 / -3.3 | 10.4 / -5.2 | 29.8·29.2·0.0 |
| Pre-Monsoon (Summer) Mar–May | 181.1 | 62.9 | 14.7 / 5.1 | 17.6 / -0.8 | 23.5·67.5·1.0 |
| Monsoon (SW) Jun–Sep | 838.3 | 117.8 | 18.7 / 11.4 | 19.5 / 8.7 | 1.0·96.0·25.0 |
| Post-Monsoon Oct–Dec | 49.7 | 25.5 | 13.4 / 1.4 | 18.1 / -4.4 | 43.0·49.0·0.0 |
State figures are a simple average across 4 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 / long-term. The October 2023 South Lhonak event demonstrated the severe downstream flood risk posed by Sikkim's high-Himalayan glacial lakes, an area of growing scientific and disaster-management concern.
Monsoon (Jun-Sep). Highly localised extreme-rainfall events on Sikkim's steep terrain can produce fast-moving, dangerous flash floods.
Monsoon (Jun-Sep). Steep slopes throughout the state are prone to monsoon-triggered landslides, frequently affecting road connectivity.
Winter. High-altitude areas face avalanche risk and periodic heavy snowfall.
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).