June through September is the only practical window for visiting Ngari. The Mount Kailash kora, the Guge ruins, and the high-altitude roads are all accessible during this period, daytime temperatures are bearable (10–20°C in Ali, colder at altitude), and the occasional summer shower does not prevent travel.
Outside this window, the difficulties multiply rapidly. October is transitional — some roads remain open, but the nights are increasingly cold. By November the high passes on the approach roads from Lhasa may be snowbound, and temperatures in Ali drop to minus 20°C or below. The spring months (April–May) see the roads opening again but are characterised by ferocious winds that make camping and outdoor activities unpleasant. Most organised tours to Ngari operate in July and August, when the weather is at its best and the light on the Guge ruins is extraordinary in the late afternoon.