Argentina is in the southern hemisphere, which implies that winter is from July to September and summer is from January to March.
Due to the extension of the country we can find from weather subtropical in the north to subarctic In the south. One can spend a lot of heat in the desert areas of the northwest and shiver cold in Tierra del Fuego.
Since the northeast of the country has a warm semitropical climate, which implies a dry season and a wet season (November to March). Rains are usually brief storms. Between May and September, temperatures are pleasant during the day but usually cool at night. Do not forget the raincoat if you decide to visit this area.
The northwest of the country has a climate of high temperatures in summer and mild and dry in winter. Do not forget to bring some shelter since the nights are usually cool at high altitude.
The Pampas It has few precipitations and its temperatures range from 24ºC in summer to 11ºC in winter.
The Patagonia It has very cold winters and hot summers. But keep in mind when choosing your wardrobe that in the Andes you should always wear warm clothes. It is not the first time it snows in summer.
Buenos Aires It presents a humid climate of high temperatures in summer, being able to reach 40ºC and low in winters between 0ºC and –2ºC.
In conclusion, there is no time of the year in which you can enjoy all the possibilities of Argentina, the north does not present many problems, it is possible to have more or less rain but this does not prevent you from seeing it. On the contrary, Patagonia presents different possibilities depending on what time of year you go. If you want to try the ski slopes then I recommend you go between June and September. If instead you want to enjoy the glaciers and trekking through the Andes then you must go between November and March.