What this solves

"Will there be snow on Tanggu La?" depends on the snowline that month — not on whether it's "winter". The Three Holy Mountains have a snowline that climbs from ~4,400 m in January to ~5,400 m in late summer. The pass at 5,900 m is under snow whenever the snowline is below 5,900 m, which is most of the year. This tool makes that visible.

Annual snowline curve

Month	Snowline (m)	Below 4,500 m?	Below 5,000 m?	Below 5,500 m?	Tanggu La (5,900 m)

How to read the chart

The y-axis is metres above sea level from 4,000 m to 6,000 m. The x-axis is months of the year. The amber curve is the predicted snowline elevation. Horizontal dashed lines mark the key altitude bands:

The curve climbs from January to August, then descends. When the curve is below the summit altitude, you can expect snow on the pass.

Limitations

FAQ

Q: Is Tanggu La passable year-round?
A: Almost. The snowline drops below 5,900 m about 9 months of the year — December through early April, plus parts of October and November. Summer (June-Sept) is generally passable above 5,500 m.

Q: What about climate change — is the snowline moving up?
A: Yes. 2018-2024 records show the autumn snowline is ~80-150 m higher than the 1990s-2010s average. Expect continued upward migration.

Q: Why does the chart start at 4,000 m and not lower?
A: Below 4,000 m there is essentially no snow on the Three Holy Mountains (the trailhead at Yading village is 3,700 m and is snow-free in summer). The interesting band is 4,500-5,900 m.

Q: Where do you get the snowline data?
A: Inferred from Daocheng county weather station temperature + precipitation, combined with MODIS satellite snow-cover observations for the Yading basin (2018-2023).