When to go to Argentina
Most of Argentina has seasons that are the opposite of the northern hemisphere’s, but as you would expect in a country of this size, distinct regions have climates all of their own. Buenos Aires is hot in summer (November to April) and mild in winter.
The Lake District is pretty in spring (October) and autumn (March) and fresher in these months than during the height of summer. Part of Patagonia’s charm is its unpredictability, and you should be prepared for four seasons in one day.
In the far south of Patagonia however, weather conditions can be severe during winter months, so we would discourage you from visiting in June, July or August. The arid northwestern region can be very hot during the summer (December to February), while Mendoza province is temperate year-round.
The time of year to travel will depend largely on the areas you wish to visit.
When to go to Brazil
Brazil can be visited year round. Other than the far south and southeast of the country which has a cooler period between June and September, the rest of the country has a warm tropical climate.
There is a rainy season that affects the northeast from about April to July, and Rio and the south from October to January, but in general the weather is excellent.