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

 

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 

Changes in parts a Himalayan town (Kalimpong) in 17 years

 

The lower photograph (May 2026) appears considerably greener than the one taken in May 2009. This is most likely because the pre-monsoon season of 2009 may have been significantly drier than that of 2026, resulting in lesser undergrowth, vegetation and seasonal greenery across the slopes.

The 2009 image also shows more open terraced cultivation and a clearer patchwork of agricultural land use, whereas these features appear less distinct in the 2026 photograph.

This change may partly be seasonal. Maize is normally planted during May and a good crop cover in 2026 may have obscured some of the terraces visible in the earlier image. However, a more important long-term factor is likely, the gradual abandonment of farmland caused by migration of younger populations away from rural areas to places abroad or to Indian metros. Many former agricultural slopes may now be unmanaged undergrowth and vegetation, making terraced areas less visible than before.

Across Areas A, B, C and D, several important changes are evident:

• There has been a substantial increase in built structures and settlement density between 2009 and 2026.
• This expansion would necessarily require an increase in slope cutting and road construction.
• Much of this growth appears largely unplanned, increasing pressure on already fragile Himalayan slopes.
• Inadequate or poorly maintained drainage systems in such densely populated hillside areas significantly increase the risk of landslides and slope failures, especially during periods of intense rainfall.
• The spread of unmanaged vegetation may also create an increased fire hazard during dry summer months when vegetation dries out.

The one encouraging sign in the 2026 image is the apparent recovery around the Pashyor landslide area (E). Increased vegetation cover suggests partial recovery and some degree of surface stabilization. However, in the Himalayas, vegetation recovery does not always mean that a landslide has become fully stable, as deep-seated geological weakness and drainage-related instability may still persist beneath the surface.

Overall, the photographs document the transformation of the western face of  Kalimpong from a more semi-rural Himalayan settlement into a more populated and urbanized area over the past seventeen years. They also highlight the growing challenge of balancing development with ecological and geological stability in the fragile Himalayan environment.

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

Using the Automatic Weather Station data to understand weather and rainfall (in this case, of Kalimpong)

The rainfall chart for the period May2025 to May2026 for Kalimpong is above and a brief analysis of the same here👇:
a. We had a fairly wet monsoon season (from approx May to Oct2025) characterized by 9 spikes when rainfall exceeded 90mm in a 24hr period. The season did start with some hiccups though:

Typical cloud image over North Bengal and Sikkim before the heavy rain of 19Jun2025

Warning on 13Jul2025 for the heavy rain (112.8mm) on 14Jul2025.

July is typically the wettest month of the monsoon season. In July 2025, there were four days during which rainfall exceeded 90 mm in a 24-hour period. Thereafter, rainfall gradually declined, apart from a brief spike on 12 August 2025. Total rainfall amounted to 467 mm in August and 253.2 mm in September 2025.

October 2025 was relatively dry, except for two days of intense rainfall. On 4–5 October, widespread heavy rain affected the entire region and triggered devastating landslides and flash floods, resulting in significant loss of life in Mirik.

These instances of spikes in rainfall are normally associated with convective clouds and normally consist of short, violent bursts of rainfall which cause high runoff and low infiltration of water (as such no recharge of aquifers) and only result in soil erosion, landslides and damage to roads.

 

After the 2025 monsoons, we went thru an extended 5 month period of drought-like conditions from November2025 to March2026.

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744 

Rainfall data of March/April 2026 of Sub-Himalayan W Bengal (SHWB) and Sikkim.

Despite the numerous Western Disturbances (WD) hitting the Western Himalayas during the winter of 2026, winter rains for us in the eastern end of the Himalayas were conspicuous by their absence. This was because WDs, which are responsible for our winter precipitation were tracking along higher latitudes or veering off towards the Tibetan plateau as they moved east (see satellite image above) as such never reached the Darjeeling-Sikkim Himalaya.

Forest fires in South Sikkim on 17Feb2026 due to extreme dry weather

In Kalimpong, we received our first storm and rains around mid - March 2026 but the Darjeeling-Kalimpong districts remained largely deficient in rain in Mar2026. 
Sikkim, however received far more rain in March and it is tabulated below:

Rainfall data day-wise for APRIL 2026 of some places in the Darjeeling and Sikkim Himalayas is shown below:

 

 

Location of rain gauge stations and rough zones of rainfall are shown:

Zone 1:  Sikkim, especially North Sikkim, received the heaviest rainfall
Among all areas in the SHWB–Sikkim, the highest precipitation occurred in North Sikkim (Mangan, Lachen, Lachung, Chungthang belt).
Zone 2. Plains of Dooars and Alipurduar were also very wet. The foothill districts of Alipurduar, Jalpaiguri, and the Dooars experienced substantial rainfall due to strong thunderstorm activity and moisture convergence.
Zone 3.  Darjeeling and Kalimpong hills were wet but comparatively less so Although rainfall was above normal, totals in Darjeeling and Kalimpong were generally lower than in North Sikkim and parts of the plains.
And in this region, Kurseong certainly always has the heaviest rainfall. The foothills of the Dooars ie Gorubathan and that belt also have intense thunderstorms and heavy rain.

Graphical Analysis of Rainfall and Windspeed of March and April 2026 of Kalimpong

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

8 Davis AWS stations are available in the Darjeeling Sikkim Himalaya - a brief tutorial on using the AWS.

Kindly refer STH blog of 21Nov2025 on the same subject 

Ever since two Davis Automatic Weather Stations were installed in Kalimpong under Project SHAMROCC in March 2016, I have consistently advocated for expanding the use of automatic weather stations across our region. In the Himalayas, where weather conditions can shift rapidly and the impacts of climate change are especially pronounced, timely and localized data is not a luxury—it is essential. Here, I am glad to inform you that as of now, we have 8 AWS in our vicinity from which updated weather inputs are available 24X7.

Against this backdrop, it is concerning that the extensive AWS network maintained by the India Meteorological Department (IMD), which was previously accessible to the public, has been taken off open access since around March 2025 and now requires login credentials.

AWS can transform how we understand and respond to weather in fragile mountain ecosystems. These systems automatically record and transmit real-time weather data without the need for human intervention.
In the Himalayas, where terrain is rugged and access is limited, AWS are indispensable. They provide continuous, high-accuracy data from remote locations, filling critical gaps left by traditional observation methods. This is especially important as climate change accelerates shifts in weather patterns, glacier melt, and extreme events.
AWS also play a key role in strengthening early warning systems and can help map changing rainfall patterns. 

For those interested in using the global Davis AWS system, here is quick tutorial:

1. Install the Weatherlink Mobile app from Google Playstore. You may have to create an account and register.
2. Open the app and add stations by hitting the + sign in the top left hand corner. Here searching by place names gives satisfactory results 
eg searching for 'Kurseong' will give 'STH KURSEONG NEW' result.
Touch the flag icon on the left to confirm adding the station - it will turn GREEN.
3. In our vicinity, you can add the following 8 stations:
a. Kalimpong - for 'STH AWS' (operated by SaveTheHIlls).
b. Kurseong - for 'STH KURSEONG NEW' (operated by SaveTheHIlls).
c. Ahalay - for 'AHALAY GBN AWS' (operated by Govt of WB, in Gorubathan).
d. Darjeeling - for 'ST PAUL'S SCHOOL METEOROLOGICAL STATION' (operated by SPS, Darjeeling).
e. Pedong - for 'BSA AWS-PEDONG' (operated by Bal Suraksha Abhiyan, Kalimpong).
f. Todey - for 'BSA AWS, TODEY, KALIMPONG' - (operated by Bal Suraksha Abhiyan, Kalimpong) - Todey is located in the eastern most corner of Kalimpong district, close to Bhutan.
g. Gangtok - for 'LAMA BUILDING' (privately operated).
h. Gangtok - for 'SSDMASEEDS' (operated by Sikkim Govt).
4. Your phone display should look something like this👇

Do experiment with the various features which are on the app to receive updated weather information from the DAVIS AWS located in our area as well as all over the world.

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744