Summer is the rainy season; it can be miserable in the lowlands.
Overland transportation becomes difficult if not impossible in some areas.
Climbing is dangerous, and trekking and biking tedious.
February to April have plenty of religious festivals.
August to October is a great time to visit the Salar de Uyuni.
Good for budget hunters.
Although winter, expect mostly sunny days throughout Bolivia but cooler temperatures in the Altiplano.
Reliable weather makes for easier transit, and better climbing, trekking and mountain biking.
August is the most popular month.
Prices are generally higher than during the rest of the year.