"The climate of the territory of Colonias varies according to the proximity of the chain of the Andes, the altitude, the abundance of watercourses, and the direction of the winds. The temperature in May, June and July is mild and agreeable, moderately cool in the morning and evening, varying between 53·6° and 76·6° from 6 p.m. to 6 a.m., and from 76·6° to 89·6° between 10 a.m. and 4 p.m. during the hottest months (September to December). Rarely does the thermometer rise or fall above these extremes. The normal temperature does, however, suffer a sudden fall when the cold south winds blow that are known as _surazos_; they come in September and produce violent storms with great and almost daily variations in the temperature, which may give rise to affections of the lungs and throat as the sequel to sudden chills. The force and direction of the winds contribute greatly to modify the salubrity of any region; places reputed to be unhealthy have become notably healthy when the forest has been opened or closed in a given direction. "The great defect of the climate here is the abundance of the rains. They fall continually through the whole rainy season, which lasts from December to May. The vapours of the Atlantic are brought up by the east winds, which are prevalent at this season; on reaching the Cordillera they are chilled as the air expands and loses heat with its increasing altitude; then the vapours condense and fall in torrents of rain, which often lasts for whole days together. But these rains are never cold, so they are not unpleasant as such rains would be in Europe; one braves them without thinking anything of it, as in Europe one braves a summer shower. "When it does not rain (the dry season lasts from June to November) the climate is delightful; the middle of the day is hot, with a somewhat heavy heat, although the sky is usually covered with a diaphanous mist which tempers the rays of the sun. "Floods are caused not only by rains in the western mountain regions, but also by local rains. They are dependent on the slope of the surface and the insignificant fall of the rivers. When the larger rivers are full the tributaries rise because their waters are dammed up or even flow backwards. The waters then become stagnant in every sense of the word, and decompose rapidly through the action of the heat and the vegetable and other detritus which they contain; at such times they produce paludian fevers; principally in April and May, when the waters begin to fall and the larger rivers receive the supplies of stagnant waters released from their tributaries. As the fall continues the mud left uncovered on the banks becomes an additional cause of fevers.