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September Weather in San Juan, Peru

Last updated: August 27, 2025

In September, the average temperature in San Juan, Peru is a mild 13°C (56°F). Expect lows of 5°C (41°F) and highs reaching up to 19°C (67°F). The region experiences about 72 mm (2.9 in) of precipitation across 20 days, coupled with an average humidity of 53%, making for a refreshing atmosphere.

September Temperature in San Juan

In September in San Juan, the average temperature is 13°C (56°F). Maximum temperatures can reach 19°C (67°F) while minimums can drop as low as 5°C (41°F). This mild weather makes it a great time for travelers to enjoy outdoor activities and explore the local sights.

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 13°C (56°F), with highs reaching up to 19°C (67°F) and lows dropping to around 5°C (41°F).
JanFebMarAprMayJunJulAugSepOctNovDec545555555454555555555555
Data source: Temperature data for San Juan generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in San Juan

In San Juan in September, the precipitation amount is 72 mm (2.9 in) over the course 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 72 mm (2.9 inches) of precipitation spread over approximately 20 days.
JanFebMarAprMayJunJulAugSepOctNovDec22924424612560231926729976129
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in San Juan

In San Juan in September, humidity is 53%. With an average temperature of 13°C (56°F), this humidity feels like a cool and refreshing embrace, making for a pleasant experience while traveling. It's comfortable enough to explore without feeling overheated, but travelers may still want to bring a light jacket for those slightly damp moments.

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 53%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%89%90%89%83%69%56%51%53%68%82%87%
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 is 16, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, making it crucial to take protective measures. For detailed information, you can refer to 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 16, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec181918171411131416181818
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.
 TemperaturePrecipitationHumidityUV
January Weather12°C (55°F)229 mm (9.0 inches)89%extreme
February Weather13°C (55°F)244 mm (9.6 inches)89%extreme
March Weather13°C (55°F)246 mm (9.7 inches)90%extreme
April Weather13°C (55°F)125 mm (4.9 inches)89%extreme
May Weather12°C (55°F)60 mm (2.3 inches)83%extreme
June Weather12°C (55°F)23 mm (0.9 inches)69%extreme
July Weather13°C (55°F)19 mm (0.7 inches)56%extreme
August Weather13°C (55°F)26 mm (1.0 inches)50%extreme
September Weather13°C (56°F)72 mm (2.9 inches)53%extreme
October Weather13°C (55°F)99 mm (3.9 inches)68%extreme
November Weather13°C (56°F)76 mm (3.0 inches)81%extreme
December Weather13°C (55°F)129 mm (5.1 inches)87%extreme

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