Extreme rainfall event in Kalimpong town on 28May2026 (instant rainfall intensity > 500mm/hr)

Flooded street in Kalimpong town at around 04.15pm/28May2026 
 

 Meteorological conditions and warnings for what started OFF as a perfectly normal day
 I checked IMD forecasts, warnings and satellite imagery as I normally do each morning and found it was perfectly normal, in fact there was a slight improvement from a day earlier. There was a YELLOW warning for thunderstorm in place but that is more or less the norm through out this part of the year, for this region:

Extracts from IMD Midday Weather Bulletin for 28May2026 issued by RMC, Kolkata

 

Infra -Red (IR) Satellite Imagery of 28May2026 afternoon period

Satellite image of 12.15pm which shows no major convective buildup around Kalimpong, even though there were clouds west of us, in Nepal. 
It was around this time that we had the first burst of rainfall - which I reported on 'Hazard Alerts' our WhatsApp group. A member of the group, quipped that 'there was no rain even in Kalimpong town' which is about a km away from my home - so all in all it was perhaps just a very localized shower. Excerpt of my post is below:

The rainfall returned at around 3.45pm,and this time it was serious, with intense thunder, heavy rainfall and hail at places. Excerpt of my post is below:

Satellite image of 4.15pm (below) shows an increase in clouding especially in Nepal but still does not have the 'WHITE' clouds (in IR imagery) associated with intense cumulonimbus buildups and strangely, only Kalimpong had intense thundershowers whereas there was little rain over the other neighboring hill towns. The fact that it was very localized is borne out by the fact that there was no formal RED warning from IMD or the SACHET app.

The second burst of rain turned out to be certainly the most intense rainfall I have ever experienced - luckily, like most thunderstorms, it moved towards a NE direction after sometime and rainfall decreased. 

Placed above are the rainfall and wind charts which I have downloaded from the SaveTheHills Davis Vantage Pro2 AWS which is installed at my home.
The salient findings about the thunderstorm from the above chart are:
a. We had 82.8mm of rainfall in approx one and half hours.
b. Max (instantaneous) intensity of rainfall exceeded 500mm/hr

 

24hr Rainfall (in mm) data of 28May2026 (IMD):
On 28May2026,there was no major weather system which gave Kalimpong this rainfall, rather it was an isolated cell which gave us this very localized rainfall and therein lies the danger - such weather is very difficult to forecast and difficult to detect in satellite imagery.

Kalimpong 79.2; Siliguri 40.5; Darjeeling 1.2; Pedong 2; Gangtok 2.1; Mangan 0
  

Damage/Casualties
As per the information available to me, except for damage to electric poles at places and a number of trees which were uprooted, there has not been any major damage to lives or property due to yesterday's extreme rainfall event.
This maybe due to the fact that in May2026, Kalimpong has had only 125.2mm of rain prior to yesterday's deluge and that we had only 9mm of rain in the last week.
Lucky us.

Verified video

Location: Next to Kodamull building, RCM Road Kalimpong

Need of the hour: Cleaning, maintenance, and upgradation of the drainage system.

If Kalimpong — or any mountain town — is to withstand such torrential volumes of storm water, we must urgently address the condition of our drainage infrastructure. Existing drains need regular cleaning and maintenance, while the entire system requires systematic upgradation to cope with increasingly intense rainfall events.

Photo video credits: Naresh Changia, Kalimpong

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744 

Extreme rainfall event in the Eastern Himalayas: 04/05Oct20205 (Part II - 'The damage and fatalities in Nepal and Bhutan')

The October 2025 rains (see previous blog) were among the most intense to strike Eastern Nepal, the Darjeeling Himalayas, and Bhutan in recent years. The storm system, which crept in from northern Uttar Pradesh and Bihar, tracked east-northeast, impacting Eastern Nepal — including Kathmandu — first. The devastation it caused has been extensively covered by the media. Below, we’ve compiled a selection of key excerpts:

Nepal

Rainfall data (mm): Kathmandu 145, Rautahat 330, Ilam 330mm (reported 37 fatalities)

Fatalities, damage and cost:
a. 66 fatalities have been reported, 69 people are missing. 37 people died in Ilam district.
b. Huge damage on development infrastructure like roads, bridges and drinking water projects across Koshi province amounting to Nepalese Rs2.06 billion. Road projects worth about Rs190 million have been lost in Ilam alone.Bridges worth an additional Rs385 million have been destroyed. 226 homes were reported submerged in Kathmandu and a total of 4,059 households affected (ReliefWeb / GDACS summary of national reports).
c. Across Panchthar, Taplejung, Sankhuwasabha, Solukhumbu and Okhaldhunga, dozens of rural roads have been blocked or buried under landslides. Of the 73 roads, 44 still remain completely obstructed, while 12 of 23 motorable bridges have been totally destroyed. A total of 20 suspension bridges remain impassable due to flood damage.

Bhutan

Bhutan lies directly to the east of Kalimpong district (West Bengal) and Sikkim. As the powerful October 2025 storm swept across the Darjeeling–Sikkim Himalayas, it reached Bhutan on 5 October, bringing with it widespread devastation. The rainfall recorded during the event is shown in the map above.
Like Nepal, Bhutan is crisscrossed by several major rivers — Jaldhaka, Diana, Torsa, Sunkosh, Raidak, Jayanti, and Kaljani — which flow from its mountains into the fertile plains of North Bengal and Assam. These rivers are lifelines for irrigation and agriculture in the region. However, intense rainfall in Bhutan’s highlands often translates into dangerous flooding in the plains downstream.

Fatalities and damage reported

As per The Bhutanese, '3 people are likely dead as two persons are reported missing in Haa Dzongkhag due to flash floods in Sertena, Gakiling Gewog and one was washed away in Kazhi in Wangduephodrang. 1 body from Haa was recovered on 6 October 2025 from Cooch Bihar'.
Further '17 bailey bridges, six suspension bridges, three culvert bridges, three wooden bridges and three private bailey bridges were washed away'. Details of the damage are available here.
According to Kuensel, Bhutan’s national newspaper, “across Bhutan, numerous roadblocks, landslides, and washed-out bridges have cut off several communities. The southern and western highways have reported significant disruptions, and several homes have been damaged or flooded.”

One of the most critical impacts was on the country’s extensive hydropower infrastructure. Authorities in North Bengal were placed on high alert after a technical failure at the Tala Hydropower Dam caused it to overflow, sparking fears of downstream flooding in the Dooars region.
In response to the severe weather, five major hydel projects — Tala, Suchhu, Dagachhu, Punatsangchhu, and Chhuka — were temporarily shut down. This unprecedented situation not only disrupted power generation but also highlighted the growing vulnerability of Himalayan infrastructure to extreme weather events.

Further details on the damage to Bhutan’s dams can be found here.

Praful Rao,
SaveTheHills
savethehills@gmail.com
9475033744