Last updated: August 27, 2025
In September, the average temperature in San Juan, Mexico hovers around 24°C (75°F). Expect a minimum of 18°C (64°F) and a maximum of 32°C (91°F), offering a warm climate that's perfect for outdoor activities. However, be prepared for a fair amount of rain, with 166 mm (6.5 in) of precipitation spread over 22 days. Don't forget to stay hydrated, as the average humidity levels are a high 83%!
In September in San Juan, the average temperature is 24°C (75°F). Maximums can reach 32°C (91°F) and minimums can be as low as 18°C (64°F). This pleasant climate makes San Juan an ideal destination for travelers seeking warm weather and comfortable conditions.
In San Juan in September, the precipitation amount is 166 mm (6.5 in), occurring over a span of 22 days.
In San Juan in September, humidity is 83%. With an average temperature of 24°C (75°F), this humidity feels like a warm blanket enveloping you, which can be quite stifling for traveling. You may find yourself frequently seeking shade or air conditioning, and it's wise to stay hydrated while exploring.
In San Juan in September, the maximum UV index is 12, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, underscoring the importance of sun protection. For detailed information, you can check the 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 | 17°C (63°F) | 11 mm (0.4 inches) | 74% | high |
| February Weather | 18°C (65°F) | 37 mm (1.5 inches) | 66% | very high |
| March Weather | 20°C (68°F) | 2 mm (0.1 inches) | 61% | extreme |
| April Weather | 22°C (72°F) | 1 mm (0.0 inches) | 56% | extreme |
| May Weather | 24°C (76°F) | 2 mm (0.1 inches) | 61% | extreme |
| June Weather | 26°C (78°F) | 73 mm (2.9 inches) | 73% | extreme |
| July Weather | 24°C (76°F) | 217 mm (8.6 inches) | 82% | extreme |
| August Weather | 25°C (76°F) | 255 mm (10.0 inches) | 83% | extreme |
| September Weather | 24°C (75°F) | 166 mm (6.5 inches) | 83% | extreme |
| October Weather | 23°C (74°F) | 68 mm (2.7 inches) | 78% | extreme |
| November Weather | 21°C (69°F) | 13 mm (0.5 inches) | 77% | very high |
| December Weather | 18°C (64°F) | 24 mm (0.9 inches) | 78% | high |