thumb|upright=0.75|The Mesopotamia (land between rivers), the area between the [[Paraná River|Paraná and the Uruguay rivers]]
The Mesopotamia or is the humid and verdant area of northeast Argentina, comprising the provinces of Misiones, Entre Ríos, and Corrientes. The landscape and its characteristics are dominated by two rivers: the Paraná and the Uruguay.
When Spanish settlers came to the area, the two parallel rivers and the lush area between them drew comparisons to Mesopotamia (, 'land between rivers') in modern-day Iraq, and it was decided that the Argentine region be named after the Iraqi region. The region shares many of its ecological features with neighboring regions of Argentina and with parts of Brazil, Paraguay, and Uruguay.
Mesopotamia has some of the most popular tourist attractions in Argentina, mainly the Iguazú Falls, the Iguazú National Park, and the Jesuit mission stations in Misiones. The Iberá Wetlands in Corrientes are an extensive area of flooded forest similar to Brazil's Pantanal.
The region is part of the Brazilian central plateau. The whole region has high rainfall, Under the Köppen climate classification, it has a humid subtropical climate (Cfa). The main features of the climate are high temperatures and abundant rainfall throughout the year. Rainfall is abundant throughout the year, because much of this region lies north of the subtropical high pressure belt, even in winter, meaning that it is exposed to moist easterly winds from the Atlantic Ocean throughout the year. With abundant precipitation throughout the year, water deficiencies and extended periods of droughts are uncommon and much of the region has a positive water balance.
Precipitation
thumb|View of the [[Alto Paraná Atlantic forests in the Misiones Province.]]
With the exception of Misiones Province which receives abundant precipitation throughout the year, precipitation is slightly higher in summer than in winter and generally decreases from east to west and from north to south. Average annual precipitation ranges from less than in the southern parts to approximately in the eastern parts of Misiones province. Spring (September–November) is similar to fall, with a mean precipitation of . The lower mean annual temperature recorded in Bernardo de Irigoyen, despite being located further north than Posadas is due to its higher altitude, resulting in a cooler climate. The southern parts of Corrientes province have cooler temperatures and have a climate more similar to Entre Ríos Province, where mean annual temperatures range from in the south to in the north. During heat waves, temperatures can exceed in the summer months while in the winter months, cold air masses from the south can push temperatures below freezing causing frost.