Argentina’s seasons run opposite to those of Europe and North America: summer is December to February, autumn March to May, winter June to August and spring September to November. Because the country stretches 3,694 km from the subtropical north to Tierra del Fuego, each season plays out very differently from province to province. In January Buenos Aires averages highs of 30.1 °C and Mendoza 32.8 °C, while Ushuaia reaches only 13.6 °C; in July the capital’s highs fall to 15.5 °C and Ushuaia’s to 4.6 °C. Rain also follows the seasons differently by region: Salta gets about four-fifths of its 738 mm between December and March, Mendoza’s dry Andean foothills see only 238 mm a year, and the Río de la Plata coast is wet in every month. Two winds give the year its character: the dry, hot zonda that pours down the Andes into Mendoza and San Juan, and the cool pampero that sweeps north across the Pampas after summer heat waves.
January: Peak Summer, From 30 °C in Buenos Aires to 13.6 °C in Ushuaia
January is the hottest month across most of the country. In Buenos Aires, measured at the Central Observatory in Agronomía, the daily mean is 24.9 °C and the average high 30.1 °C, with humid nights around 20 °C and the year’s most sunshine, nearly 273 hours. Heat waves come and go, usually lasting less than a week, and the city’s all-time record of 43.3 °C was set on 29 January 1957. In January 2022 a heat wave caused power cuts affecting more than 700,000 households in the metropolitan area.
The end of a heat wave in the Pampas usually arrives with the pampero, a cold, dry wind from the south. Its front brings violent thunderstorms, followed by cooler, drier air. The Pampas thunderstorms are known for the most frequent lightning and some of the highest convective cloud tops in the world, and the region from Córdoba and Santa Fe to Entre Ríos and Greater Buenos Aires forms South America’s tornado alley, active between November and April.
At the far end of the country, January is Ushuaia’s warmest month, but warm is relative: the average high is 13.6 °C, the average low 5.4 °C, and night frost is possible even in summer. Daylight lasts more than 17 hours, and those long days make the austral summer the main visiting season in Tierra del Fuego.
February: Summer Rains in Salta and Hailstorms in Mendoza
The northwest has a summer rainy season, almost the opposite of Patagonia’s pattern. Salta receives 197.1 mm in January and 147.3 mm in February, with rain on about 14 or 15 days in each, often in short, heavy bursts. Highs stay in the mid- to upper 20s and humidity is above 80 % in February and March, so the valleys are at their greenest.
Mendoza, further south at the foot of the Andes, has the same summer-wet timing but far less water. It averages 40.8 mm in February and 238 mm in the whole year, and its sunshine totals almost 3,000 hours. Farming in this arid region depends on irrigation. Summer’s main hazard here is hail: storms forced up against the Andes foothills cost the region an estimated US$50 million a year in wine production and US$30 million in fruit.
March: Vendimia and the First Cool Nights
March is still warm, with Buenos Aires averaging 27.0 °C in the afternoons, but the nights start to ease. In Mendoza the harvest is under way, and the Fiesta Nacional de la Vendimia, the national grape-harvest festival, reaches its climax in Mendoza city in the first week of March with hundreds of dancers and performers, the selection of the Reina Nacional de la Vendimia and a large fireworks display. The first official festival was held in 1936. Mendoza’s average high in March is 28.1 °C, and its nights fall to 15.7 °C, a wide daily swing typical of the dry Cuyo region.
Buenos Aires, by contrast, stays wet: March brings about 120 mm and April 130 mm, close to the summer figures. The capital has no real dry season, and autumn and winter rain often comes with the sudestada, described below.
April and May: Autumn Fog on the Río de la Plata and a Dry Northwest
Autumn is short in the Pampas. Buenos Aires’s mean drops from 22.0 °C in March to 18.2 °C in April and 14.8 °C in May, and the air grows damper, with relative humidity near 79 % by May. That humidity makes the city prone to moderate and heavy fog in autumn and winter. In the northwest the rain ends abruptly: Salta falls from 107 mm in March to 42 mm in April and less than 10 mm in May, opening months of dry, sunny weather.
In the far south, Ushuaia’s average high drops from 12.2 °C in March to 9.4 °C in April and 6.9 °C in May, and sunshine falls below 100 hours a month. May also marks the start of the zonda season in Cuyo, which runs to November.
June and July: Winter, Snow in the South and the Zonda in Cuyo
July is the coldest month for Buenos Aires, Mendoza and Salta. The capital averages 11.0 °C, with highs of 15.5 °C and lows of 7.5 °C, and cold spells from Antarctica arrive almost every year. The city’s record low is −5.4 °C, on 9 July 1918, and snow is so rare that the fall of 9 July 2007 was described as its first major snowfall in 89 years; the Central Observatory has logged snow only three times since 1906, in 1918, 1928 and 2007. Mendoza’s July nights average 2.0 °C under clear skies, while Salta’s winter days stay pleasant at about 20 °C before dropping to 2.9 °C at night.
Ushuaia’s days shrink to just over seven hours of daylight, highs average 4.5 °C in June, and snow, sleet and rain showers are frequent. This is ski season: Cerro Castor, 26 km from the city, normally runs from June to October, the longest season among Argentina’s main ski centres.
Winter is also zonda season. The zonda is a foehn wind: air crossing the Andes loses its moisture on the way over, then descends the eastern slopes from crests around 6,000 m and warms as it goes. In about 90 % of cases it blows between May and November, most strongly in La Rioja, San Juan and northern Mendoza, where the mountain barrier is highest. It usually starts in the afternoon and lasts from one to twelve hours, though it can come and go for two or three days, with gusts of up to 120 km/h. It can push temperatures as high as 35 °C even in winter and fuel wildfires, while at high altitude the same system brings blizzards known as viento blanco.
August and September: Sudestada Rains and the Driest Weeks in the North
Late winter warms steadily. Buenos Aires’s mean climbs from 11.0 °C in July to 13.0 °C in August and 14.9 °C in September. This is the main season of the sudestada, a sudden shift of cold southerly winds to the south-east, most likely between July and October. It moderates the cold but loads the air with Atlantic moisture, bringing long spells of rain, rough seas and storm surges that flood the low shores of the Río de la Plata and the Salado basin.
In the northwest, August and September are the driest and clearest months of all. Salta gets just 2.3 mm in August, its humidity falls to about 56 % in September, and frosts are common: the airport’s record low is −9.4 °C, in August. Mendoza’s spring begins with highs of 21.8 °C in September and lows of 7.8 °C, and the zonda can still bring sudden bursts of heat.
October and November: Spring Jacarandas and the Return of the Rains
In Buenos Aires, spring brings mild days, from 22.6 °C highs in October to 26.0 °C in November, and violet jacarandas flowering along avenues and plazas. October is one of the city’s wetter months, with about 123 mm on ten rain days, as thunderstorms return to the Pampas. In the northwest the rains come back gradually, from 24 mm in October to 59 mm in November in Salta.
In the far south the days lengthen quickly, though Ushuaia’s highs reach only 10.1 °C in October and 11.5 °C in November, and snow can still fall in the summer months there.
December: Midsummer Heat in the Chaco and Cuyo
By December summer is back in full. Buenos Aires averages 29.0 °C highs and Salta 28.4 °C, its warmest month by day. Mendoza’s December record is 44.9 °C, the highest at its airport station, and the national record belongs to the north: the World Meteorological Organization lists 48.9 °C at Rivadavia, in Salta Province, on 11 December 1905, as the highest temperature recorded in Argentina and South America. The Chaco, covering Chaco and Formosa provinces and parts of their neighbours, is Argentina’s hottest region, with a mean annual temperature of 23 °C. At the other end of the scale, the national cold record is −32.8 °C, at Sarmiento in Chubut, on 1 June 1907.
For travel, the reversed calendar means the south is best from November to March, when Patagonia’s days are long, while the northwest is easiest from May to September, when Salta and Jujuy are dry. Buenos Aires is most comfortable in spring and autumn. The reasons why January is midsummer here are explained in our piece on Earth’s tilt and the seasons; the regional climate zones are mapped out in the climate of Argentina guide, and anyone heading south should read up on the best time to visit Patagonia before booking.