The rainfall of about 18 inches is concentrated in the summer season, 85 per cent falling between November and March. During this time the town is somewhat isolated by swollen streams and washed out trails: hence here, as on the plateau, there is a distinct seasonal distribution of the work of planting, harvesting, moving goods, and even mining, and of the general commerce of the towns. There is an approach to our winter season in this respect and in respect of a respite from the almost continuously high temperatures of summer. The daytime temperatures of summer are however mitigated by the drainage of cool air from the surrounding highlands. This, indeed, prolongs the period required for the maturing of plants, but there are no harmful results because freezing temperatures are not reached, even in winter.
| MONTHLY TEMPERATURES, COCHABAMBA, 1906 | ||||
| Month | Mean Min. | Mean Max. | Mean Range | Daily Mean |
| January | 55.7 | 72.25 | 16.65 | 63.3 |
| February | 61.2 | 71.3 | 10.1 | 65.5 |
| March | 59.8 | 72.6 | 12.8 | 65.5 |
| April | 55.06 | 70.8 | 15.74 | 62.2 |
| May | 50.9 | 68.7 | 17.8 | 59.1 |
| June | 47.1 | 65.6 | 18.5 | 55.6 |
| July | 44.8 | 64.9 | 20.1 | 54.1 |
| August | 49.9 | 68.0 | 18.1 | 58.2 |
| September | 55.6 | 73.2 | 17.6 | 63.7 |
| October | 56.1 | 73.4 | 17.3 | 64.0 |
| November | 58.1 | 75.7 | 17.6 | 66.2 |
| December | 58.6 | 73.9 | 15.3 | 65.8 |
Figs. 109-113—Temperature curves for locations in the montaña, July and August, 1911. The curves are based on hourly readings with interpolated readings for such critical occurrences as the appearance of cloud or rain. Dry bulb readings are shown by solid lines, wet bulb by dotted lines, and breaks in the continuity of the observations by heavy broken lines. [109] is for Pongo de Mainique, August 20 and 21; Fig. 110 for Yavero; Fig. 111 for Santo Anato, August 11 and 12; Fig. 112 for Sahuayaco, August 20, and Fig. 113 for Santa Ana, July 30 to August 1.