The weather is fresh with an annual average temperature of 13ºC, but with a great thermal amplitude, registering maximum absolute of 40ºC and minims of -17ºC, the winds of the southwest and the northwest predominate and the precipitations reach to 330 annual mm.   It is possible to emphasize that the weather is but cold much in the mountain zone, which does that the flora and the fauna of that place are very different from the one from the plain.   Barren cold and with eternal snows in summits of mountains contrasts with the green one of level, the apt one for all type of cultures.   This diversity of landscapes causes that Tunuyán has an ample tourist supply in the four stations of the year. 

The primitive inhabitants were huarpes absorbed by puelches in their advance towards the north.   The area also underwent the irruption of tribes pehuenches and huiliches that for more than four centuries harassed to the establishments with their incursions.  

the water availability in the plain with grounds apt for agriculture and the connection with the North oasis, favored the valuation of this sector.   Two linkings cross with predominant direction the North-South the department:  The Main Mountain range and the Frontal.   To the east of this one extends the Piedemonte.   The Main Mountain range is a continuous cord with flyovers, discharge and steep, it constitutes the limit with Chile.   Constructed by orogenia tertiary, it offers volcanic manifestations like the Tupungato and San Jose.   Its more important linking is the Cordón del Portillo and crossing the Paso del Portillo  to 4.  369mts, is acceded to the valley of the Tunuyán river soon to happen to Chilean territory.   Hills like Pircas (5. 600mts)m, Meiji (5.500mts), Three Tips of Love (5.500mts) and Bell tower (4.900mts). 

Flora:  pasture  for the cattle, yareta, líquenes, ferns, penny royal, mosqueta rose, paño, thyme, lume.   Fauna:  cóndores, eagles, vizcachas, hares, foxes, pumas, guanacos, ducks and piuquenes. 

The Frontal Mountain   is one  Paleozoic structure,  eroded, fractured and rejuvenesced by effects of the Andean folding.   It reaches heights that oscillate between  6.  000 mts to north and 4.  900 mts  to south.   With smaller glaciations development, it displays deep furrows products of the erosion, broken and waterfall that trims the mountain.  

Plain:  Crossed by the Tunuyán river, here is based the population and economic development of the department.   The weather is fresh, with great thermal amplitude.  

Flora:  chañar, jarilla, atamisqui, totora, junquilo, retamillo, cortadera, pichana.   Fauna:  small lizards, serpents, hares, perdices, rabbit of the wall, otter, pititorras, catfishes and taguas. 

Agriculture:  diversified, plantations of apple trees, pear trees, peach trees, walnuts and cherry trees.   One cultivates in addition essential tomato, garlic, pepper, oregano and other grass and of course there are 2.  000  hectares of vineyards in the heat of production. 

The winds of the West provide humidity, with precipitations between 600 and 900 annual mm,   they are fed by glaciers developed from the Tupungato to the Piuquenes hill.   As the mountain range is dividing of waters, the Eastern front gives to origin to a dense network of torrents and streams that come together to form the Tunuyán river.   These waters are derived from the dock Valle de  Uco.   The more important tributary streams of the Tunuyán river are El Yaucha, Las Tunas, Pircas and Grande.