September Weather in San Juan, Peru

Last updated: August 27, 2025

In September, the average temperature in San Juan, Peru is a warm 26°C (80°F). Expect a range between a pleasant minimum of 20°C (68°F) and a scorching maximum of 35°C (96°F). Be prepared for 152 mm (6.0 in) of precipitation over 20 days, coupled with an average humidity of 56%.

September Temperature in San Juan

In September in San Juan, the average temperature is 26°C (80°F). Maximums can reach 35°C (96°F), while minimums can drop to as low as 20°C (68°F). It's a great time to visit for those who enjoy warm weather and outdoor activities.

September Weather in San Juan: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in San Juan, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Juan, September typically has an average temperature of 26°C (80°F), with highs reaching up to 35°C (96°F) and lows dropping to around 20°C (68°F).

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

September Precipitation in San Juan

In San Juan in September, the total precipitation amount is 152 mm (6.0 in) spread over a period of 20 days.

September Precipitation Trends in San Juan

The chart displays monthly precipitation patterns in San Juan, 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 San Juan, September typically receives around 152 mm (6.0 inches) of precipitation spread over approximately 20 days.

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

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Millimeters (mm) Inches (in)

September Humidity in San Juan

In San Juan in September humidity is 56%. With an average temperature of 26°C (80°F), this humidity feels like a warm embrace that adds a noticeable weight to the air, making outdoor activities feel more intense and requiring extra hydration for comfort while traveling.

September Average Humidity in San Juan

This chart illustrates the average monthly humidity levels in San Juan, 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 San Juan is approximately 56%, 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 San Juan

In San Juan in September, the maximum UV index reaches 13, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's crucial to take protective measures. For detailed information, you can check the Hourly UV Index in San Juan.

Maximum UV Index Levels in San Juan for September

The chart shows the monthly maximum UV Index (UVI) for San Juan 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 San Juan typically reaches 13, which falls under the extreme exposure category.

Data source: San Juan 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 San Juan Compares to Other Months

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

This table compares monthly weather conditions in San Juan, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	26°C (79°F)	251 mm (9.9 inches)	84%	extreme
February Weather	26°C (79°F)	226 mm (8.9 inches)	82%	extreme
March Weather	26°C (79°F)	321 mm (12.7 inches)	84%	extreme
April Weather	26°C (79°F)	305 mm (12.0 inches)	87%	extreme
May Weather	26°C (79°F)	223 mm (8.8 inches)	89%	extreme
June Weather	25°C (78°F)	193 mm (7.6 inches)	82%	extreme
July Weather	25°C (78°F)	145 mm (5.7 inches)	69%	extreme
August Weather	26°C (79°F)	107 mm (4.2 inches)	58%	extreme
September Weather	26°C (80°F)	152 mm (6.0 inches)	56%	extreme
October Weather	26°C (80°F)	188 mm (7.4 inches)	62%	extreme
November Weather	26°C (80°F)	233 mm (9.2 inches)	77%	extreme
December Weather	26°C (79°F)	273 mm (10.7 inches)	88%	extreme