Buenos Aires enjoys a lovely climate throughout the year, but the winter months of July and August are often favoured for their temperate conditions, while skiing begins in earnest by July and the Tango Festival takes place in August. Mendoza has a fantastic, Mediterranean climate but keep in mind that the Wine Festival falls within March. Salta and the Northwest enjoys clear skies and warm days in autumn (March - May) and, although the nights are chilly, it’s still lovely in winter.
By spring (September - November), the Lake District is blooming with wildflowers while summer (December - February) means Patagonia becomes more accessible and enjoys longer days. Winter in Patagonia should be avoided as many facilities close and the temperatures are frigid. The area around Iguazu Falls is tropical, which remains pleasant all year but after the spring rains, the Falls are particularly spectacular.