In this part of Bolivia, which embraces the cities of La Paz, Corocoro, Oruro, Potosi, and the great mining center of Huanchaca, Colquechaca, etc., there are four seasons—spring, covering the months of September, October, and November; summer, the months of December, January, and February; autumn, the months of March, April, and May; and winter, the months of June, July, and August. As the transition from one season to another, as thus classified, is not attended by any marked change of weather, a more popularly recognized division is that of the wet or summer season, from December to May, and the dry or winter season, from June to November. During the wet months of December, January, and February, which usually cover the rainy season, and the cold months of June, July, and August, this section of the country is subject to extremes of heat and cold. The difference between the indoor and outdoor temperature being so marked and fires being simply used for cooking, the only means of keeping comfortable is to remove one's overcoat or wraps on leaving the house and don them upon entering. During the other months of the year, the weather is, for the most part, mild, uniform, and exceedingly agreeable.
The wet season is marked by frequent and terrific hail and thunder storms, and so copious is the rainfall that frequently the inconsiderable mountain streams are suddenly converted into impassable rivers. At this season, the La Paz River, which enjoys the distinction of being the only tributary of the Amazon which receives its waters from the eastern declivity of the Cordillera Real, becomes a rushing mountain torrent, sending its waters southward through its narrow, tortuous channel around the base of the lofty Illimani, and thence northward into the calmer currents of the Mamore.
Sucre, in the valley of the Pilcomayo; Cochabamba, in the valley of the Tapacari; and Sorata, in the Sorata River valley, enjoy perpetual spring and a climate of unsurpassed salubrity.
