Most of the rivers are fed by the thawing of snow on the peaks, and their volume of water increases considerably in spring.

The Universidad Nacional de Cuyo, founded in 1939, is the most important within these provinces, and has its campus in Mendoza, but has faculties as far as Río Negro.

[7] The Andes prevent rain–bearing clouds from the Pacific Ocean from coming in, while its latitude puts it in a band of the sub-tropical high pressure belt keeping this region dry.

[2][8] With very low humidity, abundant sunshine throughout the year, and a temperate climate, the region is suitable for wine production.

[8] The Cuyo region is influenced by the subtropical, semi–permanent South Atlantic anticyclone to the east in the Atlantic, the semi-permanent South Pacific anticyclone to the west of the Andes, the development of a low pressure system ("Chaco low") over northern Argentina and westerlies in the southern parts of the region.

[2][9] Most of the precipitation falls during the summer, when hot temperatures and high insolation lead to the development of a low pressure system ("Chaco low") situated over northern Argentina that interacts with the South Atlantic anticyclone to generate a pressure gradient that brings moist easterly winds to the region, favouring precipitation, which mostly occurs in the form of convective thunderstorms.

In the lowlands of Mendoza province, which lie at an elevation of around 440 m to 530 m, mean annual temperatures range from 18.2 to 18.7 °C (64.8 to 65.7 °F) in the northern parts to 15 °C (59 °F) in the south.

[17] In San Luis province, mean annual temperatures range from 15.8 °C (60.4 °F) in Villa Reynolds to 16.6 °C (61.9 °F) in the provincial capital.

[14] In all locations, at elevations over 3,800 m, permafrost is present while icy conditions persist year round at elevations over 4,000 m.[3] The Zonda, a Foehn wind characterized by warm, dry air can cause temperatures to exceed 30 °C (86.0 °F) in some cases while in summer, temperatures can exceed 45 °C (113.0 °F) such as in 2003.

[19][20] This wind often precedes following a cold front passage across Argentina and tends to occur when a low pressure system brings heavy rain to the Chilean side, and when an upper-level trough allows the winds to pass over the Andes to descend downwards.