Buenos Aires vs Rio de Janeiro

Based on sunshine hours, rain days, comfortable temperatures, and humidity levels, Buenos Aires edges ahead as the better destination in December. Buenos Aires offers 12 hours of daily sunshine with only 8 rain days, while Rio de Janeiro sees 10 sunshine hours and 20 rain days.

Buenos Aires sits in the comfortable travel range at 27°C. Rio de Janeiro runs hot at 30°C.

For travelers who prioritize dry weather, Buenos Aires is the stronger choice in December. Buenos Aires receives 2 more hours of sunshine per day, which matters for sightseeing and outdoor activities.

Buenos Aires reaches an average high of 27°C (81°F) and drops to 19°C (66°F) at night during December. The daily temperature range is 8°C, meaning moderate variation throughout the day.

Rio de Janeiro averages 30°C (86°F) for the high and 23°C (73°F) for the low, with a daily range of 7°C. The 3°C difference is noticeable but not dramatic.

Both cities are in the Southern Hemisphere, so they share the same seasonal pattern in December.

Buenos Aires receives approximately 88 mm of rainfall across 8 rain days during December. You can expect rain roughly every other day.

Rio de Janeiro sees 226 mm over 20 rain days. That makes Buenos Aires the drier option by 12 rain days and 138 mm of total precipitation.

Humidity also differs: Buenos Aires averages 70% while Rio de Janeiro sits at 78%. Rio de Janeiro will feel muggier, especially at higher temperatures.