September Weather in Buenos Aires, Costa Rica

Last updated: August 23, 2025

In September, the average temperature in Buenos Aires, Costa Rica hovers around 19°C (67°F). Expect a comfortable range with minimums dipping to 14°C (58°F) and maximums peaking at 27°C (80°F). However, be prepared for 299 mm (11.8 in) of precipitation spread over about 29 days, contributing to an average humidity level of 81%. Plan your activities accordingly!

September Temperature in Buenos Aires

In September in Buenos Aires, the average temperature is 19°C (67°F), with maximums reaching 27°C (80°F) and minimums dropping as low as 14°C (58°F). This comfortable climate makes it an ideal time for outdoor adventures and exploring the local attractions.

September Weather in Buenos Aires: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Buenos Aires, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Buenos Aires, September typically has an average temperature of 19°C (67°F), with highs reaching up to 27°C (80°F) and lows dropping to around 14°C (58°F).

Data source: Temperature data for Buenos Aires generated using information from the Copernicus Climate Change Service.

September Precipitation in Buenos Aires

In Buenos Aires in September, the total precipitation amount is 299 mm (11.8 in) over a period of 29 days.

September Precipitation Trends in Buenos Aires

The chart displays monthly precipitation patterns in Buenos Aires, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Buenos Aires, September typically receives around 299 mm (11.8 inches) of precipitation spread over approximately 29 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Buenos Aires

In Buenos Aires in September humidity is 81%. With an average temperature of 19°C (67°F), this humidity feels like a heavy blanket enveloping you, making travel somewhat uncomfortable as sweat clings to your skin and the air feels thick, prompting you to seek shade and hydration frequently.

September Average Humidity in Buenos Aires

This chart illustrates the average monthly humidity levels in Buenos Aires, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Buenos Aires is approximately 81%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Buenos Aires

In Buenos Aires in September, the maximum UV index is 14, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, so it's crucial to take precautions. For the detailed hourly UV index in Buenos Aires, you can check here.

Maximum UV Index Levels in Buenos Aires for September

The chart shows the monthly maximum UV Index (UVI) for Buenos Aires in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Buenos Aires typically reaches 14, which falls under the extreme exposure category.

Data source: Buenos Aires September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How September Weather in Buenos Aires Compares to Other Months

Weather in Buenos Aires varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Buenos Aires, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Buenos Aires, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	19°C (66°F)	50 mm (2.0 inches)	68%	extreme
February Weather	19°C (66°F)	42 mm (1.6 inches)	68%	extreme
March Weather	19°C (67°F)	35 mm (1.4 inches)	66%	extreme
April Weather	20°C (68°F)	113 mm (4.5 inches)	67%	extreme
May Weather	20°C (68°F)	397 mm (15.6 inches)	69%	extreme
June Weather	20°C (68°F)	288 mm (11.4 inches)	84%	extreme
July Weather	20°C (68°F)	237 mm (9.3 inches)	85%	extreme
August Weather	20°C (67°F)	354 mm (13.9 inches)	82%	extreme
September Weather	19°C (67°F)	299 mm (11.8 inches)	81%	extreme
October Weather	19°C (67°F)	490 mm (19.3 inches)	80%	extreme
November Weather	19°C (67°F)	304 mm (12.0 inches)	80%	extreme
December Weather	19°C (66°F)	86 mm (3.4 inches)	72%	extreme