Last updated: August 27, 2025
In San Juan, Peru, the average temperature in September is a mild 12°C (54°F). Daily temperatures can vary, with a minimum of 5°C (42°F) and a maximum reaching 23°C (73°F). Expect some rain, as precipitation averages 154 mm (6.1 in) over the course of 18 days. With an average humidity of 42%, it’s a comfortable month to explore!
In September in San Juan, the average temperature is 12°C (54°F). The maximum can reach 23°C (73°F), and the minimum can be as low as 5°C (42°F). It's a great time to enjoy mild weather, making it perfect for outdoor activities and exploring the local attractions.
In San Juan in September, the total precipitation amount is 154 mm (6.1 in) over the course of 18 days.
In San Juan in September, humidity is 42%. With an average temperature of 12°C (54°F), this humidity feels like a crisp, refreshing environment that encourages outdoor exploration, making it perfect for sightseeing and leisurely strolls without the discomfort of excessive heat.
In San Juan in September, the maximum UV index reaches an alarming 17, which falls under the extreme Exposure Category. With a time to burn of just 10 minutes, it's crucial to stay protected. For more details on the hourly UV index in San Juan, you can check Hourly UV Index in San Juan.
UV Risk Categories
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.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 12°C (54°F) | 304 mm (12.0 inches) | 83% | extreme |
| February Weather | 12°C (54°F) | 392 mm (15.4 inches) | 81% | extreme |
| March Weather | 12°C (53°F) | 599 mm (23.6 inches) | 88% | extreme |
| April Weather | 12°C (54°F) | 348 mm (13.7 inches) | 85% | extreme |
| May Weather | 12°C (54°F) | 188 mm (7.4 inches) | 78% | extreme |
| June Weather | 12°C (54°F) | 70 mm (2.8 inches) | 62% | extreme |
| July Weather | 12°C (54°F) | 43 mm (1.7 inches) | 44% | extreme |
| August Weather | 12°C (55°F) | 47 mm (1.9 inches) | 38% | extreme |
| September Weather | 12°C (54°F) | 154 mm (6.1 inches) | 42% | extreme |
| October Weather | 12°C (54°F) | 299 mm (11.8 inches) | 58% | extreme |
| November Weather | 12°C (54°F) | 290 mm (11.4 inches) | 69% | extreme |
| December Weather | 12°C (54°F) | 413 mm (16.2 inches) | 82% | extreme |