Dated brief, 30 August 2026 (figures were still moving). This is not a UV-index forecast for Rasuwa or Gyirong. It is a record of a disaster that sat at elevation, with sources you can open, plus one planning note if you are on high ground when monsoon rain breaks.

On the morning of 26 August, ice, rock, and mud ran from near Langtang Lirung down the Lhende into the Bhotekoshi and Trishuli. Nepal’s NDRRMA and Chinese local authorities were still counting on Sunday: on the order of 800 dead and more than 3,000 missing across both sides of the border. Reuters that day split it 781 dead / 2,502 missing in Nepal and 16 dead / 546 missing in Gyirong. Hydropower tunnels still held workers. A debris dam, then a second landslide, kept interrupting the search.

The U.S. Geological Survey told reporters the first “quake” was the collapse itself, not a tectonic trigger. University of Calgary researchers reading Planet Labs imagery for Reuters put the break near 5,200 m, with debris falling about 1,200 m to the valley floor. ICIMOD tracked the surge down the Bhote Koshi / Trishuli. Downstream at Galchhi, water was reported up by as much as nine metres in 30 minutes.

We are not a wire service. For the live casualty and rescue picture, use NDRRMA, Reuters’ reconstruction, the Kathmandu Post, and Chinese official statements from Gyirong—not this page. Tibet-side counts came only from Chinese authorities; foreign journalists were not in.

If you are on a ridge when the cloud breaks

The emergency is the water. Flood warning, higher ground, and search lines come first. What follows is only for skin that is actually in the sun while you wait.

Thick monsoon rain that hides the solar disc cuts UV. A break that throws a sharp shadow does not. Search lines and high-ground waits sit well above the valley floor. Cool, wet air is not a low-UV signal. You feel infrared leaving the skin. The index does not care.

Height and ice still raise the rate

UV still climbs as the atmosphere thins. WHO: about 10–12% per 1,000 m. That is a planning range, all else equal—not a reading for this valley today. We are not publishing a local index for Rasuwa. The 5,200 m break already in the satellite work is five of those steps above sea level. Treat the percentage as order of magnitude, not a forecast. Mechanism: higher elevation, stronger UV.

Ice and snow add a second path. WHO: fresh snow can reflect as much as 80% of UV and nearly double total exposure. A bright ice face bounces onto the chin, the underside of the nose, and the eyelids. Shade from a ridge wall or a tarp cuts what comes from above. It does not cancel what comes from the snow. That surface story is shade does not cancel UV.

Cloud is not cover if you still have a shadow

Monsoon skies are not one thing. Overcast that swallows the disc is a real cut. A hole that still prints a shadow on the mud is open-sky UV, often with bright cloud walls beside it. Broken cloud that leaves a sharp shadow can sit above a clear-sky hour—broken clouds can raise UV. Do not take the hat off because the air cooled when the shower passed.

Heat is a third false cue. Peak UV still sits near solar noon, often before a break feels warm. That lag is UV peaks before the heat.

Cover, then get back to the water

If you are actually in the sun on high ground:

1. Treat a sharp shadow as a UV hour, even if the last hour was rain and the air is cold.
2. Cover skin and eyes the way you would on any bright altitude day—hat, glasses, clothing, sunscreen on what cloth misses. Snow and ice make the eyes non-optional.
3. Do not import a lowland morning number. Recheck the live UV index for the place you stand—current, today’s peak, next few hours, as in how to use a live UV index. This page is still not a Rasuwa forecast.
4. Get back to the flood warning. Debris and rising water are the story. UV is a side risk for people waiting in the open. It is not the emergency.

Sources

Public reporting as of Sunday 30 August 2026. Nepal NDRRMA. Sunday death and missing split: Reuters, 30 August 2026. Break near 5,200 m, fall about 1,200 m, USGS, Planet Labs / University of Calgary: Reuters, 26 August 2026 and the Reuters graphics reconstruction. Galchhi rise of as much as nine metres in 30 minutes: ICIMOD as reported by Down to Earth. Also the Guardian, AFP / France 24, Al Jazeera, the Kathmandu Post, Xinhua / CCTV. Totals were still rising. WHO altitude 10–12% per 1,000 m and snow albedo up to ~80%: UV radiation Q&A and UV index Q&A. Those percentages are planning ranges, not a forecast for Rasuwa.