Buenos Aires Weather in September
Argentina · Humid Subtropical climate · Data averaged from 2020-01-01 to 2024-12-31 (5 years)
September in Buenos Aires sees average temperatures ranging from a low of 10.8°C (51.4°F) to a high of 18.1°C (64.6°F), with a mean of 14.4°C (57.9°F). Compared to the annual average of 17.6°C (63.7°F), this month is 3.2°C cooler than the yearly norm. Precipitation averages 63.5mm, making it approximately 11.0mm drier than the monthly average of 74.0mm. The city receives an average of 9.0 hours of sunshine per day during September, with relative humidity averaging 74.4%. Wind speeds reach an average maximum of 24.3 km/h. For travelers, this month offers a temperature experience in Buenos Aires, with drier-than-average conditions compared to the rest of the year.
If you're planning outdoor activities in Buenos Aires, the seasons are flipped but mild. I ran the Costanera Sur in January (summer): 30°C with 70% humidity, draining but the river breeze helped. March-April is the outdoor sweet spot: 22°C, manageable UV, empty paths. October-November is similarly ideal — jacarandas blooming, 20°C, perfect cycling weather. July (winter) brings 12°C and dampness; running is fine but mornings feel raw. UV peaks dangerously in January (11+); sun protection is mandatory between 10am-4pm. The wind off the Río de la Plata is constant and can be bracing in winter.
September vs Adjacent Months
| Metric | August | September | October |
|---|---|---|---|
| Mean Temp | 12.0°C (53.6°F) | 14.4°C (57.9°F) | 17.3°C (63.1°F) |
| Rainfall | 59.0mm | 63.5mm | 66.2mm |
| Sunshine | 8.3 hrs | 9.0 hrs | 10.6 hrs |
| Humidity | 75.3% | 74.4% | 69.1% |
| Wind | 22.8 km/h | 24.3 km/h | 25.0 km/h |
| Rainy Days | 9.2 | 9.6 | 11.8 |
Seasonal Context
September falls in Autumn in the Northern Hemisphere. Autumn sees temperatures gradually cooling from summer highs. For travelers visiting Buenos Aires in September, the data indicates mixed conditions based on the combination of temperature, precipitation, and daylight hours.
Frequently Asked Questions
What is the average temperature in Buenos Aires in September?
The average temperature in Buenos Aires during September ranges from 10.8°C (51.4°F) to 18.1°C (64.6°F), with a mean of 14.4°C (57.9°F).
How much does it rain in Buenos Aires in September?
Buenos Aires receives an average of 63.5mm of precipitation in September, spread across approximately 9.6 rainy days.
What should I pack for Buenos Aires in September?
Based on September weather data, pack warm layers, a medium jacket, and waterproof outerwear.
Is September a good time to visit Buenos Aires?
September is a cooler month, suitable for travelers who prefer mild weather and fewer crowds. Pack warm layers and enjoy indoor attractions.
Other Months for Buenos Aires
Cities with Similar September Climate (Humid Subtropical)
Data Source: Open-Meteo historical archive (2020-01-01 to 2024-12-31). Daily measurements aggregated into monthly climate normals. Coordinates: -34.61°, -58.38°. Timezone: America/Argentina/Buenos_Aires. Last updated: 2026-07-30.