1. Nepal's Monsoon Is Changing: The Hidden Risks of Nepal's Early Autumn Treks
Why September and Early October Demand Caution:
Nepal receives most of its annual rainfall during the summer monsoon. According to the 2003 record, the monsoon traditionally began in June and withdrew around the end of August or early September. However, the monsoon withdrawal is not happening in a traditional cycle now; in fact, it is extending further until early October.
For years, we believed that the rain stops in early September and the mountains are safe again. But this belief is now out of date. Climate change has put river valleys, mountain regions, and high glacial lakes at risk. We ask adventure travelers from around the world to take caution while choosing the monsoon or early Autumn season for your Himalayan adventure.
Due to this monsoon extension, international travelers get confused and think September is the beginning of the autumn trekking season. Many trekking agencies sell their trekking packages from early September, creating the impression that the wet season has ended.
But the reality is more complicated.
According to Nepal's Department of Hydrology and Meteorology, the monsoon withdrawal date is around October 4 or later.
The 2026 Nepal Monsoon Pattern
- The monsoon reached Nepal on 19 June, which is a late start.
- It began to withdraw from 4 October.
- It did not completely withdraw until October 13, and it fully left the country on 14 October.
- In the late withdrawal period, the Himalayan region received more rain than the Tarai and hill regions.
This means the first two weeks of October were still part of the monsoon withdrawal period in Nepal.
Why rainfall after the summer monsoon is particularly dangerous
The problem is not the amount of rainfall Nepal receives every monsoon. We are to be aware of the fact that by September (during the gradual monsoon withdrawal period), mountains, hills, and the surrounding soil have absorbed so much water and moisture. All these will create unstable ground, and any new rain or an earthquake will trigger heavy landslides.
The unexpected hazards travelers may encounter:
- Landslides: On trekking trails, settlements, or mountain roads blockade.
- Flash floods: Increased river discharge.
- Washed Trekking Trails: Can keep you stranded in the remote valley.
- Damaged bridges: Destroy essential river crossings.
- Road blockages: Prevent vehicle evacuation.
- Poor visibility: Prevents helicopter rescue or any mountain operations.
For trekkers following narrow Himalayan river corridors, a single destroyed bridge can disrupt an entire expedition.
What this means for travellers: For trekkers trekking through the narrow Himalayan river corridors, such incidents can disrupt an entire expedition and can put your life at stake. It also means September and early October can still be unstable. Be aware that the monsoon in Nepal now lasts till early October.
Does climate change mean Nepal's monsoon always ends later?
Not necessarily.
However, Climate Change is happening, and witnessing the affects of it in the Himalayan regions. We are also witnessing how Himalayan trekking is becoming risky at certain times of the year due to this. Climate change is affecting Himalayan temperatures, precipitation patterns, glaciers, and mountain hazards.
However, just because we had a few delayed monsoon withdrawals in Nepal, we should not interpret this as proof of a permanent trend.
Looking at the pattern of the last 5 years, what travelers need to know is that the traditional trekking seasons have indeed altered to some extent. The traditional seasonal patterns are no longer sufficient and valid for making safe adventure decisions.
Now, a crucial time has come when September or early October itineraries should be judged by studying the monsoon pattern.
- Nepal Pyramids Advice: Treat September and early October as a monsoon transitional period. For major river-valley treks, consider late October or November or Winter instead.
2. What The 2026 Floods in Rasuwa, Annapurna Circuit and Manaslu Showed Us: A Warning for Himalayan Trekkers
August and Early Autumn 2026 have been a tragic time for Nepal. Three of Nepal's best-known trekking regions experienced serious flooding, landslides, and infrastructure damage. These events remind us why mountain weather, trail conditions, and local safety information matter.
Here is the timeline, based on reports available as of 17 October 2026.
| Date | Place | What Happened |
| 26 August, 2026 | Rasuwa, Bhote Koshi and Trishuli valleys | The most devastating tsunami flash flood, causing extensive loss of life and infrastructure - thousands are expected dead. |
| 6 September, 2026 | Therang Khola, near Namrung (Manaslu Circuit) | A pre-dawn flood damaged suspension bridges in the Namrung area and disrupted trekking access along the Manaslu Circuit route. |
| 24 - 28 September, 2026 | Central Nepal | Intense late-monsoon rainfall triggered widespread floods and landslides, damaging roads, homes, and bridges. 304 landslide incidents nationwide were reported during this period. |
| 27 September, 2026 | Chame, Marsyangdi Valley (Annapurna Circuit) | Debris partially blocked the Marsyangdi River, causing flash floods that damaged houses, bridges, roads, and trekking routes. Residents evacuated to safer areas, and several trekkers were stranded. The village of Chame was highly affected. |
| 11 October, 2026 | Budhi Gandaki, Gorkha (Manaslu region) | Flash floods destroyed bridges, villages, and trekking infrastructure. More than 100 foreign trekkers were reported stranded. |
The disasters of 2026 demonstrate that Himalayan floods do not always require heavy rainfall or the outburst of glacial lakes. Even in perfectly sunny weather, a glacial avalanche or massive landslides in the river valley can trigger such catastrophic flash floods.
August 26, 2026: The catastrophic Rasuwa flood
On August 26, a massive avalanche occurred high in the Lhende Khola or Bhotekoshi near the Nepal - China border. This generated a powerful flood and debris flow that travelled through the Bhote Koshi and Trishuli river systems. This Rasuwa Tsunami Flashflood is considered one of the most devastating in the history of Nepal's natural calamities.
The disaster affected communities, transport infrastructure, and settlements across several districts, including Rasuwa, Nuwakot, and Dhading. Roads, bridges, hydropower infrastructure, and other essential facilities suffered extensive damage.
The August 26, Rasuwa Flood caused catastrophic loss of life and widespread destruction. The recorded death toll by September 19, 2026, was around 1,411 casualties, with 5,875 people still missing.
September 6, 2026: Flood damage near Namrung, Manaslu Route
Less than two weeks later, flooding along Therang Khola and the Budhi Gandaki River near Namrung caused further destruction in the Manaslu region. This destroyed bridges, homes, and local hydropower facilities.
The incident disrupted trekking trails and affected movement on the Manaslu trekking route just as the autumn tourist season was beginning. Then, the Government had to stop issuing any further permits for Manaslu Trekking until further notice.
For trekkers, this was a risk and a big blow to travelers who were dreaming of trekking in the remote valleys of Manaslu. Many treks had to be diverted to other safe trekking destinations.
September 27, 2026: Devastating floods hit Chame and disrupt the Annapurna Circuit Trek
On September 27, swelling rivers and flash floods devastated Chame, the district headquarters of Manang. It caused extensive damage to houses, roads, and bridges. Shortly after, the flood from Ghatte Khola (river) partially blocked the Marsyangdi River and caused water levels to rise dangerously. It submerged a major bridge connecting Chame to Upper Manang.
This disaster severely disrupted the Annapurna Circuit Trek. Many trekkers had to abort the trek, and much like in Manaslu, the Nepal Authority had to stop issuing any further permits for the Annapurna Circuit Trek. It was really sad to see that such a natural disaster affected trekking routes, disrupting movement at the beginning of the early autumn trekking season.
October 11, 2026: More than 100 foreign trekkers stranded in Manaslu
Then came another serious disaster.
On October 11, a flash flood swept through the Budhi Gandaki corridor in Gorkha. Much like the Rasuwa flooding, it was a debris flash flood that was devastating and tragic. This Budhi Gandaki flood damaged trekking infrastructure, bridges, homes, and other property.
Initial reports suggested that a landslide had obstructed the river, creating a blockage that eventually flooded along the Budhi Gandaki Corridor. This was the second major, disastrous, and tragic flash flood after the Rasuwa flooding.
More than 100 international trekkers were reported stranded in Jagat. Other travelers were affected around Lokpa and Chhekampar in the Tsum Valley area. Hundreds of locals fled to safety and were stranded.
However, the rescue teams, local authorities, and security agencies coordinated evacuations and safe movements during these calamities.
Lessons Learned from Nepal’s 2026 Flash Floods: A Wake-Up Call for Himalayan Tourism
The devastating floods in Rasuwa, Annapurna Circuit, and Manaslu Route showed how quickly trekking routes, bridges, communities, and tourism livelihoods can be disrupted.
The biggest lesson: In Himalayan tourism, safety must come before profits and adventure.
For Travel and Trekking Agencies
- Never prioritize bookings, itineraries, or profits over human safety.
- Verify weather, trail conditions, and access before departure and throughout the trek.
- Do a risk assessment.
- Develop evacuation plans, alternative routes, and emergency communication systems.
- Train guides in disaster preparedness, first aid, and emergency decision-making.
- Be transparent with clients about risks, cancellations and refunds.
For Trekkers and Travelers
- Understand that mountains are beautiful but unpredictable.
- Follow weather warnings and respect guides' safety decisions.
- Carry suitable insurance, emergency supplies, and communication equipment.
- Be flexible with itineraries; turning back is wisdom, not failure.
For Government and Tourism Authorities
- Establish reliable early-warning systems in trekking corridors.
- Improve monitoring of glacial lakes, landslides and river blockages.
- Strengthen bridges, trekking trails and emergency evacuation infrastructure.
- Ensure coordination among government agencies, local communities and trekking operators.
- Publish timely, verified, route-specific travel advisories rather than general warnings.
For Local Communities
- Strengthen community-based disaster preparedness.
- Protect traditional knowledge of mountain hazards.
- Identify safe evacuation routes, shelters, and communication points.
- Stop building teahouses and luxury hotels along the river corridors.
Neither the Nepal Government nor we can stop natural disasters from happening. However, better preparedness, timely warnings, responsible decisions, and stronger coordination can reduce their consequences.
The future of Nepal's tourism should not be measured only by how many trekkers we attract, but also by how safely we bring them home.
"The floods of 2026 remind us that responsible tourism is not simply about reaching a destination; it is about protecting lives, respecting nature, and building resilience together"
3. Why River Valley Treks Are Vulnerable and Risky During Monsoon and Early Autumn
The study shows that many of Nepal's most famous trekking routes begin in deep river valleys following a river upstream. In reality, this is what makes every trekking experience in Nepal beautiful and memorable. Though they are the most spectacular landscapes on Earth, they are also at risk of landslides, flash floods, and river erosion.
| Route | River Valley or Corridor | Main risk in September and early October |
| Manaslu Circuit and Tsum Valley | Budhi Gandaki River Valley and Shyar Khola (Tsum Valley) | Landslides, flash floods, swollen rivers, and damage to trekking trails and suspension bridges. Two floods in five weeks this year, 2026. |
| Annapurna Circuit | Marsyangdi River Valley and Kali Gandaki River Valley | Landslides, road blockages, river flooding, and possible snowfall at Thorong La Pass. |
| Mustang and Upper Mustang | Kali Gandaki River Valley and its upper tributaries | Flash floods, rockfalls, erosion, and road disruptions, particularly in Lower Mustang. Upper Mustang has relatively lower monsoon rainfall. |
| Lantang and Rasuwa Area | Langtang Khola, Bhote Koshi, and Trishuli River corridors | Landslides, GLOFs, debris flows, damaged bridges, and road blockages. The same corridor was hit by the 26 August 2026 flood. |
| Everest Region | Dudh Koshi, Bhote Koshi, and Imja Khola river valleys | Flight delays and landslides on the road to Ramechhap, plus the long-term glacier lake risk explained in the next section. |
Manaslu Circuit and Tsum Valley: The Budhi Gandaki corridor
The Manaslu Circuit route follows the Budhi Gandaki River. The September and October 2026 floods demonstrate why trekkers should not assume that the Manaslu Circuit is suitable for an early-autumn departure.
- Recommendation: Avoid committing to September or early-October Manaslu departures without verified route conditions.
Annapurna Circuit: Landslides along the Marsyangdi River
The Annapurna Circuit follows the Marsyangdi River valley and follows the Kali Gandaki Valley after the Thorong La Pass. The road journey towards Dharapani, or to Tatopani after the Thorong La, may be affected in case of natural calamities.
- Recommendation: Prioritize late October to November or winter or Spring for the Annapurna Circuit trek if you are trekking and driving is involved in some sections.
Mustang and Upper Mustang: A rain shadow does not eliminate risk
Upper Mustang is often described as a suitable monsoon trekking destination because it lies under the rain shadow area. However, Mustang frequently involves the Kali Gandaki corridor, and during the monsoon or early autumn season it can create significant access problems.
- Recommendation: Always verify the access route, transportation arrangements, and weather warnings.
Langtang and Rasuwa: High-mountain flooding and disrupted access
The Langtang region is certainly very fascinating and gorgeous. However, the August 2026 Rasuwa disaster illustrates the vulnerability of the region during the monsoon or early Autumn season.
- Recommendation: Though the trekking route to Langtang and Gosaikunda is unaffected by the 2026 tsunami flooding, yet its wise to know the conditions of the roadways that connect the town from where you start and end your trek.
Everest Base Camp and the Khumbu: Different terrain, different hazards
During monsoon and early Autumn season periods, the Everest region will have a different story of poor weather, flight delays or cancellations, or limited helicopter operations.
The Khumbu region is also at risk of GLOF, which includes the Imja Tsho near the Island Peak region. This, on the other hand, is very unpredictable.
- Recommendation: When planning for Everest Base Camp or Island Peak trips, have contingency days for flight cancellations and stay away from settlements close to the river corridor.
4. Climate Change, Everest Region and Imja Tsho: The Hidden Risks in the Everest Region
Monsoon rain is only the tip of an iceberg. In reality, Global Warming and Climate change are transforming the Himalayan environment. In Nepal's Himalayan region, Global Warming is melting glaciers and filling new lakes behind unstable walls, which are at risk of causing devastating GLOFs.
Imja Tsho is the best example:
- Imja Tsho is at a height of 5,010 metres, around 10 km south of Mount Everest, at the base of Island Peak.
- It is the fastest-growing glacial lake in Nepal.
- It holds roughly 75 million cubic metres of water.
- It could be the worst-case GLOF, in any case.
- Out of 3,000 glacial lakes in Nepal, 392 are identified in the Everest Region.
According to research by the International Centre for Integrated Mountain Development (ICIMOD), glaciers across the Hindu Kush Himalaya lost ice substantially faster during 2011–2020 than during the previous decade.
How warming and temperature rise affect mountain hazards:
- Glacier retreat.
- Glacial lake expansion
- Avalanches or landslides creating temporary river blockages.
- Sudden flood release: A failed lake dam or landslide blockage can generate a destructive downstream flood.
- Cascading impacts: Floodwater may carry sediment and boulders, damaging bridges, roads, villages, and hydropower facilities.
The most concerning hazard in the Himalayan region of Everest is a GLOF, a glacial lake outburst flood.
Imja Tsho: What Everest trekkers should understand
Imja Tsho (Imja Lake) is a high-altitude glacial lake in the Everest region near the base of the most popular trekking Peak, Island Peak. Over the years, Imja Lake has been studied due to its rapid expansion and the high risk of explosion.
However, every year, Nepal is closely monitoring Imja Tsho with international support, but that does not eliminate the imminent risk. Trekkers and Climber should therefore understand the possibility of glacial-lake hazards and be careful while doing these sections during the monsoon or early Autumn season.
What climate change means for future Himalayan trekking
During the coming years, the potential consequences include:
- More challenges with extreme rainfall and flooding.
- Landslides and road or trekking trail blockages.
- Glacier retreat and expansion of high-altitude glacial lakes.
- Damage to trekking routes, connecting bridges, roads, and other mountain infrastructure.
5. When to Trek Nepal Instead? Safer Seasons and Essential Planning Advice
The purpose of this article is not to discourage travelers, neither we are asking you to abandon your Himalayan dreams. We are simply trying to encourage you to make smart decisions regarding your Nepal Himalayan adventures.
Recommended Trekking Seasons in Nepal
| Trekking Season | Conditions and Advantages | Safety Consideration |
| Late October - November (Autumn) Preferred trekking window | Most favourable, monsoon has withdrawn, improved mountain visibility, and progressively drier trails. Particularly suitable for EBC, Annapurna, and other established Himalayan routes. | Monsoon Flood and landslide-damaged bridges, roads, and trails may remain unsafe even after weather conditions improve. Confirm route accessibility before departure. |
| December - February (Winter Adventure) | Getting very popular season for trekking and climbing, with clear mountain views, quieter trails, and opportunities for lower-altitude trekking adventures. | Snow, ice, slippery trails, extreme cold, high-pass and teahouse closures may restrict demanding routes. Choose itineraries suited to winter conditions. |
| March - May (Spring) | Generally milder temperatures, blooming rhododendron forests and other flora, and excellent Himalayan scenery. Popular for trekking and mountaineering. | Pre-monsoon storms, altitude-related hazards, and changing local weather conditions require careful monitoring and preparation. |
Essential Questions to Ask Before Booking a Trek
| Questions for trekking operators | Why it matters |
| Has the trekking route been inspected following recent floods, landslides, or storms? | This confirms whether recent natural hazards have affected route safety. |
| Are all sections you plan to use currently accessible? | Helps identify damaged infrastructure and unsafe crossings. |
| Are there alternative routes available? | Reduces the risk of unexpected delays or being stranded. |
| What procedures are followed in cases of similar natural disasters? | This helps determine whether the operator has clear safety and cancellation protocols. |
| What emergency evacuation arrangements are available? | This is to ensure that emergency response is available in remote areas. |
| Does my travel insurance cover emergency evacuation or any such trip disruptions? | Helps protect travellers against potentially substantial medical and logistical expenses. |
Frequently Asked Questions About Trekking in Nepal During Monsoon and Early Autumn
Is it safe to trek in Nepal in September?
No, September is generally a higher-risk month for trekking in Nepal due to the extended monsoon. Some treks remain possible, but careful risk assessment is essential.
Is early October a good time to trek in Nepal?
Early October can be operated in many trekking destinations, but it is still not a safe window for trekking. It is the monsoon subsiding period when the wet valley is still unstable. Nepal's monsoon did not fully withdraw until October 14 in 2026. Travelers should check forecasts and get recent updates from their agencies.
When does the monsoon season end in Nepal?
With the change in climate, it's been a decade now that Nepal's monsoon withdrawal period has gone as far as early October. However, this withdrawal date may vary annually. In 2026, the monsoon withdrew completely on October 14. Travelers should check with their respective agencies.
What is the best time to trek in Nepal?
Spring (March-May), autumn late October to November and winter (December-February) are the most favorable periods. Conditions vary by region, altitude, and year.
Is the Manaslu Circuit safe after the October 2026 flood?
Yes, the Manaslu Circuit is safe now (updated 20 October 2026). The October 11, 2026 Budhi Gandaki flood damaged bridges and trekking routes in the Manaslu region, but now it's back in operation. However, the rehabilitation of infrastructure is still happening at a good pace.
Can I trek the Annapurna Circuit in September?
Trekking the Annapurna Circuit in September is possible in some conditions, but it carries significant monsoon-related concerns. Late October to November is generally a more favorable choice.
Is Upper Mustang safe during the monsoon?
Upper Mustang is very safe since it lies in the rain shadow area. However, in case of Jomsom flight cancellation, travel through the Kali Gandaki corridor can still be unsafe due to landslides, river flooding, and road damage.
Can Imja Tsho cause a glacial lake outburst flood?
Imja Tsho is regularly monitored and studied for potential outburst flood hazards. There are continued observations, and lots of risk-reduction projects have lowered the risk, but still unpredictable.
How is climate change affecting trekking in Nepal?
Climate change is accelerating glacier loss and contributing to changes in Himalayan weather and mountain systems. For more details, check our blog post: How Climate Change Is Reshaping Our Trekking.
Plan Your Nepal Trek With Local Experts Who Put Safety First
At Nepal Pyramids Trekking & Climbing, we believe a successful Himalayan adventure is about reaching a destination. It is about experiencing the mountains responsibly, respecting local communities, and returning home safely.
Whether you are planning Everest Base Camp, the Annapurna, or any Himalayan climbing expedition, choosing the right season should be the first step.
