Bolivia is situated on the southern hemisphere, between the cancer of Capricorn and the Equator. The seasons can be thus divided into two seasons, rather then into four seasons like in Europe or United States; the dry season (winter) and the rainy season (summer).
The dry season duration is roughly from May to October, and the rainy season from November to April. During the dry season, Altiplano has sunny and dry weather, the days are relatively warm, but during the night the temperatures can fall deep below zero, even during the day there is significant difference between the temperatures in the sun and in the shade. Mountains are without cloud cover and are clearly visible. Unfortunately this visibility can be distorted by dust (dust comes from the unsealed roads, and is also taken into air by winds) and smoke (smoke is the result of yearly burning of grazing grounds and jungle in the Amazon basin), which can appears from the end of July until September. The countryside has desolate dry look, colours being yellow, brown and grey. The weather in the lowlands is pleasant, relatively warm, unless there are southern winds, so called “Suraso” which bring cold air from Antarctic. The water levels in the rivers are low and the extensive wetlands are nearly dried up. This is the best time to observe animal life, as the animals concentrate around the lagoons which are the last sources of water and food in what has been during the summer extensive wetlands. In this period all the roads are transitable.