Generally speaking, the best time to travel Tibet is between April and October, and peak season is from May to September. The best months are May, June, September or October as July and August are rainy months.
Most annual rainfall comes in the rainy season that starts from May to September, when the precipitation covers 90 percent of the whole year. Usually it rains at night in Lhasa, Shigatse and Chamdo area. The precipitations gradually decrease from 5000 millimeters in the lower part of southeast to just 50 in the northwest.
If you are traveling by road, then avoid the rainy season as roads are often closed due to mudslides, cave-ins and mire. However, if you are planning to be in and around Lhasa, and getting there by air, then feel free to travel at any time from April to October.
Climate in southeastern Tibet (e.g. Nyingchi) is gentle and temperate with the average temperature of eight degrees;
In eastern Tibet, May, June and September are the height of the tourism season with July or August being the rainy season. In winter, roads are all blocked by heavy snow. Landslides are frequent occurrences, making travel difficult.
In northern Tibet, the average temperature is subzero and winter lasts from October through May or June. July and August are the best time to visit the area. You will be welcomed by warm temperatures, intense sunshine, beautiful scenery and festive events.
In western Tibet (e.g. Nakqu), the average temperature is below zero degree;
Southern Tibet is balmy during May through October, and most rainfall is between June and September. Heavy rains during the nights block roads and make travel difficult, though the scenery is at its best and there are also great festive events held.
In Lhasa and the central part of Tibet, temperatures range from 29 degrees C (84 degrees F) in summer to minus 16 degrees C (3 degrees F) in winter. Sunlight in Lhasa is so intense that the city is called Sunlight City. The thin Tibetan air can neither radiate nor absorb heat, resulting in temperature extremes during both day and night. April to October is the best time to visit Tibet, avoiding the coldest months from December to February. Rains are in August.
Everest Area: Best time: Early May to early October but clear views
are not guaranteed due to high altitude clouds. December to February
is very cols and snow.