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 September. Buenos Aires offers 4 hours of daily sunshine with only 4 rain days, while Rio de Janeiro sees 9 sunshine hours and 11 rain days.

Buenos Aires sits in the comfortable travel range at 16°C. Rio de Janeiro is also comfortable at 27°C.

For travelers who prioritize dry weather, Buenos Aires is the stronger choice in September. Rio de Janeiro receives 5 more hours of sunshine per day, which matters for sightseeing and outdoor activities.

Buenos Aires reaches an average high of 16°C (61°F) and drops to 8°C (46°F) at night during September. The daily temperature range is 8°C, meaning moderate variation throughout the day.

Rio de Janeiro averages 27°C (81°F) for the high and 19°C (66°F) for the low, with a daily range of 8°C. There is a notable 11°C gap between the two cities, so expect a very different feel.

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

Buenos Aires receives approximately 50 mm of rainfall across 4 rain days during September. Rain is occasional, so a light rain jacket should suffice.

Rio de Janeiro sees 88 mm over 11 rain days. That makes Buenos Aires the drier option by 7 rain days and 38 mm of total precipitation.

Humidity also differs: Buenos Aires averages 65% while Rio de Janeiro sits at 78%. Rio de Janeiro will feel muggier, especially at higher temperatures.