Trekkers must be prepared for extremes in climate even in the middle of summer. A hot sunny day can turn cold and miserable in a matter of minutes, especially at higher elevations. Night temperatures at 4500m and above routinely fall below freezing even in July and August! At other times if the year it gets colder. In midwinter in north-western Tibet, minimum temperatures reach minus 40oC. Yet Tibet is a study in contrasts, and in the summer months a scorching sun and hot blustery winds can make even the hardiest walker scurry for any available shade. Between the two extremes the Tibetan climate is ideal for walking - cool and dry - but always be prepared for the worst.