What this solves

Single-variable weather stats are misleading. "Average sunny days in July is 30%" sounds OK until you realise that on a 3-day trek you need three good days in a row — and those tend to cluster or not. The tool computes the joint probability of all four gates passing on the same day, which is the actual constraint on a summit day at 5,900 m.

Pick a month and look at the year

Which month do you want to inspect?

Strictness of gates

How to read the chart

Each bar is one calendar month. Bar color:

Numbers are 2018-2023 derived from Daocheng weather station. Mountain conditions (5,900 m) are harsher — multiply by ~0.85 to estimate the gate pass-through at altitude.

Limitations

FAQ

Q: Why is July only 12% if each individual gate is > 50%?
A: Joint probabilities multiply. If visibility, dry, wind, and no-snow are each 50-60% in July, the joint probability is 0.55 × 0.55 × 0.55 × 0.7 ≈ 12%.

Q: What's a "best week" — how is that defined?
A: The 7-day window (any consecutive 7 days within the month) with the highest joint probability. Often it falls in mid-month for October, late-month for May.

Q: My trip is fixed for July. What do I do with this information?
A: Plan for the day-loop (no high kora), bring rain gear, and accept that you might not see the Three Peaks. You can still have a great trip — just different goals.

Q: How does "strictness" change the numbers?
A: Strict raises each gate's threshold (e.g., wind < 20 km/h instead of 30 km/h). This drops each bar's height by ~30-40%. Useful for technical inner-kora attempts; relaxed is fine for the day-loop.