The climate of Argentina varies from region to region, as the vast size of the country and wide variation in altitude make for a wide range of climate types. Summers are the warmest and wettest season in most of Argentina, except for most of Patagonia, where it is the driest season. The climate is warm and tropical in the north, mild in the center, and cold in the southern parts, that experience frequent frost and snow. Because the southern parts of the country are moderated by the surrounding oceans, the cold is less intense and prolonged than areas at similar latitudes in the Northern Hemisphere. Spring and autumn are transition seasons that generally feature mild weather.
Many regions have different, often contrasting microclimates. In general, the northern parts of the country are characterized by hot, humid, rainy summers and mild winters with periodic droughts. Mesopotamia, in the northeast is characterized by high temperatures and abundant precipitation throughout the year with droughts being uncommon. West of this lies the Chaco region, which is the warmest region in Argentina. Precipitation in the Chaco region decreases westwards, resulting in the vegetation changing from forests in the east to shrubs in the west. Northwest Argentina is predominantly dry and hot although the rugged topography makes it climatically diverse, ranging from the cold, dry Puna to thick jungles. The center of the country, which includes the Pampas to the east and the drier Cuyo region to the west has hot summers with frequent tornadoes and thunderstorms, and cool, dry winters. Patagonia, in the southern parts of the country has a dry climate with warm summers and cold winters characterized by strong winds throughout the year and one of the strongest precipitation gradients in the world. High elevations at all latitudes experience cooler conditions, and the mountainous zones can see heavy snowfall.
The geographic and geomorphic characteristics of Argentina tend to create extreme weather conditions, often leading to natural disasters that negatively impact the country both economically and socially. The Pampas, where many of the large cities are located, has a flat topography and poor water drainage, making it vulnerable to flooding. Severe storms can lead to tornadoes, damaging hail, storm surges, and high winds, causing extensive damage to houses and infrastructure, displacing thousands of people and causing significant loss of life. Extreme temperature events such as heat waves and cold waves impact rural and urban areas by negatively impacting agriculture, one of the main economic activities of the country, and by increasing energy demand, which can lead to energy shortages.
Argentina is vulnerable and will likely be significantly impacted by climate change. Temperatures have increased in the last century while the observed changes in precipitation are variable, with some areas receiving more and other areas less. These changes have impacted river flow, increased the frequency of extreme weather events, and led to the retreat of glaciers. Based on the projections for both precipitation and temperatures, these climatic events are likely to increase in severity and create new problems associated with climate change in the country.
Seasons In Argentina, the climate is divided into four, well defined seasons, those being winter, spring, summer and autumn.
Winter
In winter (June–August), the northern parts of Argentina are generally warm, the central parts mild, and the southern parts cold with frequent frost and snow. The climate of the southern parts of the country is moderated by the surrounding oceans, resulting in cold weather that is less intense and prolonged than at comparable latitudes in the northern hemisphere. The northern parts of the country have the warmest temperatures, with an average of ; the central parts are cooler, with an average of . In the extreme south, mean temperatures are below . At higher altitudes in the Andes, average winter temperatures are below . June and July temperatures are normally similar to each other; however, in August temperatures see a rise of about .
Precipitation varies a lot during the winter months. The highest are in the extreme northern part of the Littoral region and northwestern parts of Patagonia, where mean winter precipitation exceeds . Most of the humid Pampas, averages between while in the north, in areas bordering the Andes, it averages less than .
Spring
Spring (September–November) is similar to autumn, with mild days and cool nights. During mid-October a large variety of wild and urban flora are in bloom. Temperatures range from in the north to in the center, and in most of Patagonia. Tierra del Fuego Province and the higher altitudes of the Andes have the coolest springs, with mean temperatures below . Temperatures grow warmer as spring progresses.
During spring, precipitation in the country varies, with the greatest amounts being in northern Buenos Aires Province and the Littoral region, where the average precipitation exceeds . Arid regions (Arid Diagonal) have the lowest spring precipitation, with an average precipitation of less than .
Summer
In summer (December–February), temperatures range from an average of in the north to a mean of in the center of the country except for the southeastern parts of Buenos Aires Province, where temperatures are cooler in summer due to the maritime influence. In the extreme south of the country, the temperature averages ; at very high altitudes, the average is below .
During summer, mean precipitation varies throughout the country: the eastern parts of Salta Province, Jujuy Province, northern Tucumán Province and all of Misiones Province are the wettest, receiving more than of precipitation during the season. Most of the Littoral region and Buenos Aires Province, average between . On the other hand, the Patagonia region is dry, with precipitation averaging less than – and occasionally below – much lower than other regions; Patagonia receives a monthly precipitation of . In the central and northern parts of the country, January is usually the wettest month, with an average monthly precipitation of in most places, even exceeding in some places.
Autumn
Autumn (March–May) is generally mild. Some southern natives forests and vineyards display red and orange autumn foliage, especially in mid-April. Frost arrives notably earlier in the south and later in the north. Mean temperatures can exceed in the northern parts of the country, while they can touch in most of the central parts of the country, and less than at the higher altitudes. As autumn progresses, mean temperatures fall in all regions, with March warmer than May. In the north, mean temperatures range from in March to in May. In the central parts of the country, mean temperatures in March are between , dropping to in May. The mean temperature in Tierra del Fuego Province in the extreme south is , and occasionally lower.
Precipitation is highest in northeast Argentina and lowest in the Patagonia and Cuyo regions. In northeast Argentina, mean precipitation can exceed while in most of Buenos Aires Province and northwest Argentina, mean autumn precipitation ranges between . In most of the western parts of northwest Argentina, Patagonia (except for western Patagonia where precipitation is higher, averaging ) and Cuyo regions, precipitation can average less than . In the northwest, precipitation decreases as autumn progresses, ushering in the dry season. For example, in Tucuman Province, March averages more than of precipitation while May averages less than . In contrast, precipitation increases in Patagonia, particularly in the western parts where May precipitation can exceed .
Factors that influence the climate Different meteorological factors affect the Argentine climate. Some of these factors are local while others come from other countries.
Geographic factors
The most important geographical factors that influence the climate of Argentina are latitude, elevation, and distance from the sea. With Argentina extending from 22oS to 55oS, there are differences in the amount of incoming solar radiation and the amount of daylight received in each season, which affects temperature. Thus, temperatures decrease from north to south due to the differences in latitudes.
Although the centre and the eastern parts of the country are mostly flat, the west is mountainous. Both the Andes and Sierras Pampeanas affect the climate of Argentina, leading to differences in temperature, pressure, and spatial distribution of precipitation depending on the topography and altitude. Here, the Andes exert an important influence on the climate. Owing to the higher altitudes of the Andes north of 40oS, they completely block the normal westerly flow, preventing low pressure systems containing moisture from the Pacific Ocean from coming in. Thus, much of Argentina north of 40oS is dominated by wind circulation patterns from the South Atlantic High. South of 40oS, the Andes are lower in altitude, allowing much of Patagonia to be dominated by westerly winds and air masses from the Pacific Ocean. However, the north–south orientation of the Andes creates a barrier for humid air masses originating from the Pacific Ocean. This is because they force these air masses upwards, cooling adiabatically. Most of the moisture is dropped on the Chilean side, causing abundant precipitation and cloudiness while on the Argentine side, the air warms adiabatically, causing it to become drier as it descends. Thus, an extensive rain–shadow is present in much of Patagonia, causing it to receive very little precipitation. The Sierras Pampeanas influences the climate on a much smaller scale than the Andes.
Distance from the sea is another important geographic factor. Owing to the shape of the country, the close proximity to the ocean means that most of the country, excluding the north is moderated by the surrounding oceans, leading to lower thermal amplitudes than comparable latitudes in the northern hemisphere. The two main currents that impact the climate of Argentina are the Brazil Current from the north and the Malvinas Current from the south (a branch of the Antarctic Circumpolar Current). The Brazil Current transports warm subtropical waters southwards while the Malvinas Current transports cold, subantarctic waters northwards. The Malvinas Current cools the coastal areas, particularly during winter when the current is stronger. Thus, coastal areas of the Pampas have cooler summers and a longer frost period owing to the cold Malvinas Current. As well, it is the main factor in making Tierra del Fuego colder than at comparable latitudes in the northern hemisphere in Europe since it is influenced by the cold Malvinas Current rather than the warm North Atlantic Current.
Atmospheric Circulation
The South Atlantic High and the South Pacific High both influence the pattern of winds and precipitations in Argentina. Owing to the greater height of the Andes at latitudes north of 40oS, much of Argentina is dominated by wind circulation patterns from the South Atlantic High. The South Atlantic High transports moisture from the Atlantic Ocean to Argentina. This occurs throughout the year due to the atmospheric pressure being lower on land than in the ocean. Much of the north and central parts of the country are affected by the South Atlantic High, with a strong influence in the eastern parts than in the west. This is due to the eastern parts being more frequently affected by the South Atlantic High, causing precipitation to decrease westwards.