Climatic map of the Province of Salta, Argentina
The province is located in the tropical zone and has a warm climate in general, though it has marked variation in climate types owing to the variation in altitudes. The orientation of the Andes influences the distribution of precipitation within the province.
The easternmost parts of the province have a semi-arid climate with a dry winter season. The mean annual temperature and precipitation are 20 °C and 500 millimetres. Temperatures can reach up to 47 °C during summers, while they can fall down to ?5 °C during winters.
The first slopes of the Andes force the moist, easterly winds to rise, provoking very high condensation leading to the formation of clouds that generate copious amounts of rain. The eastern slopes of the mountains receive between 1,000 to 1,500 mm of precipitation a year, although some places receive up to 2,500 mm of precipitation annually owing to orographic precipitation. Most of the precipitation is concentrated in the summer, with winters being dry. The high rainfall on these first slopes creates a thick jungle that extends in a narrow strip along these ranges, creating an area of great species diversity. At higher altitudes on these slopes, the climate is cooler and more humid, with the vegetation consisting of deciduous and pine trees.
Between the high altitudes to the west and the low plains to the east lie the valleys. The climate of these valleys is temperate, allowing for human settlement and agricultural activities. Mean annual precipitation is around 1,000 mm, most of it during summer. Mean temperatures exceed 20 °C during the summer, while during winter, they are below 14 °C.
Further west, the Altiplano is a plateau at 3,000 m to 4,000 m above sea level. The climate is arid and cold: high temperatures vary little (since the warmer season is cloudy, and the coolest is sunny), ranging from 14 °C to 21 °C; night temperatures go from 6 °C in midsummer, to -8 °C in midwinter, and extremes under -15 °C might be recorded. All rain falls exclusively in the summer, with values between 200 mm and 400 mm in total. Several salt flats exist in this area.
At the highest altitudes found in the western parts of the province, the climate is arid and cold, with large diurnal ranges (temperature range between day and night).