The Chaco is hot. Summer (December to March) is fierce — daytime temperatures routinely hit 40°C and the humidity is heavy; this is also the rainy season, with sudden afternoon storms. Winter (June to August) is warm and dry, with pleasant 20-25°C days and cool nights — the best time to visit.
The major event is the Bienal Internacional de Escultura, held in July of even-numbered years, when international sculptors work in public and the city fills with art lovers. Otherwise, the cooler months suit a couple of days of walking, day trips to Corrientes and the Chaco protected areas.