The weather in Argentina is tricky to summarise as the geographical diversity of the country gives rise to hugely varied weather conditions between the north and the south. If you are planning to travel the full length of the country then you need to be well prepared with appropriate clothing as well as taking into account the time of year you will be travelling in.
The seasons in Argentina fall in the following months:
The subtropical north and northeastern parts of Argentina can get humid and sticky and the best time to visit is during the winter months when the temperature drops a bit and travelling becomes easier.
The central region is generally hot and humid and there is not a very dramatic change in climate between the seasons. Cities like Buenos Aires and Córdoba can therefore be slotted into your trip at any point.
The western side of Argentina is flanked by the Andes where the climate changes depending on how high the altitude. You may also find yourself amidst a zonda windstorm where hot, dry, dust-filled gusts swirl around for hours and sometimes even several days.
Heading southwards to subpolar Patagonia the climate really depends on how low you go, however it is more often than not cold and rainfall is high. It is best to try and head south during the summer months of December to March. To the east the temperature is milder whereas to the southernmost tip you will find yourself in extremely cold weather conditions. The tierra del fuego is pretty much consistently freezing and wet so make sure you pack accordingly!