The kora season runs from May to October, with June and July the most popular months. Even in summer, temperatures at the Drolma La (5,630 m) can drop below freezing at night, and snowstorms are possible at any time. The Saga Dawa Festival, held on the full moon of the fourth Tibetan month (usually May or June), draws the largest concentration of pilgrims of the year — the atmosphere is extraordinary, but guesthouses fill completely.
Avoid November through April: snow can close the Drolma La entirely, and temperatures at base are brutal. The monsoon season (July–August) brings higher precipitation but the mountain remains walkable for most of the time.