May marks the final month of the pre-monsoon season and normally receives 257.5 mm rainfall over the Sub-Himalayan West Bengal (SHWB) and Sikkim region according to IMD (1971–2000 normals). The month is usually characterized by thunderstorms, squalls, hailstorms, and increasing moisture influx from the Bay of Bengal ahead of the southwest monsoon.
May 2026 was a highly variable month, with rainfall distributed unevenly across the region. Some locations experienced rainfall well above the long-term normal, while others remained comparatively dry.
A notable feature was the occurrence of several intense rainfall events between 13–17 May and again around 22–26 May, particularly affecting Sikkim and parts of the Himalayan foothills.
The extraordinary rainfall which took place in Kalimpong on 28May2026 is covered in an earlier blog.
- Mangan – 642.3 mm
- Gangtok – 584.5 mm
- Sevoke – 440.4 mm
- Kurseong – 434.2 mm
- Khanitar – 92.4 mm
- Darjeeling – 131.2 mm
- Kalimpong – 213.0 mm
The IMD normal rainfall for May over SHWB & Sikkim is 257.5 mm.
Above Normal
Mangan (+149%)
Gangtok (+127%)
Sevoke (+71%)
Kurseong (+69%)
Banarhat (+43%)
Alipurduar (+43%)
Siliguri (+30%)
Damthang (+18%)
Near Normal
Neora (−8%)
Below Normal
Kalimpong (−17%)
Darjeeling (−49%)
Khanitar (−64%)
Mangan and Gangtok experienced exceptional rainfall.
Sevoke, Banarhat, Alipurduar and Siliguri all received abundant rainfall. The foothill belt was particularly active during thunderstorm episodes.
Darjeeling itself was surprisingly dry compared with neighbouring Kurseong and Kalimpong. This highlights the highly localized nature of pre-monsoon convection and terrain-induced rainfall.
Praful RaoSaveTheHills
savethehills@gmail.com
9475033744
