The vast Pampa region fanning out 500 miles from Buenos Aires has an average annual rainfall range of 20 inches in the west to 40 inches in the east.
The Andean region extends from the dry north to the heavily glaciated and ice covered mountains of Patagonia. Its trajectory includes the dry mountains and desert west of Cordoba and south of Tucuman and embraces the irrigated valleys on the eastern slopes and foothills of the Andes. Annual precipitation ranges from 4 to 24 inches in the arid regions and 20 to 120 inches in the heaviest rainfall areas.
Patagonia is a region of arid, windswept plateaus, covering about 300,000 square miles. Except for some irrigated valleys, this is poor, scattered pastureland. Far south, the weather is continuously cold and stormy; the region has no summer, and winters can be severe.
The alluvial plain of the Chaco in the north has a subtropical climate with dry winters and humid summers. Rainfall decreases from 60 to 20 inches, and temperatures reach 120 °F.
The Argentine Mesopotamia, which consists of the provinces between the Uruguay and Parana Rivers, is made up of floodplains and gently rolling grassy hills The greatest precipitation falls in the extreme north of Misiones Province, where it amounts to about 80 inches yearly.
Buenos Aires, located on the southern bank of the Rio de la Plata, borders on the vast Pampa. The terrain within the city varies from low flatland only inches above the high tide line to slightly rolling countryside with a maximum elevation of 129 feet. Average rainfall in Buenos Aires is 39 inches, distributed evenly throughout the year. Humidity is high year round (the yearly mean is 76%). High humidity makes winters seem colder and summers hotter. Abrupt temperature changes are experienced throughout the year, bringing relief from summer's heat and winter's cold.