Last updated: August 27, 2025
In September, the average temperature in San Sebastian, Mexico hovers around a pleasant 20°C (68°F). Expect a minimum of 14°C (57°F) and a maximum of 28°C (83°F), making it an ideal time for various outdoor activities. However, be prepared for ample rainfall, with a total precipitation of 502 mm (19.8 in) over 29 days. With an average humidity level of 83%, it's a month that blends warmth with a touch of tropical moisture.
In September in San Sebastian, the average temperature is 20°C (68°F). Maximum temperatures can reach 28°C (83°F), while the minimum can drop as low as 14°C (57°F). It's a great time to visit for those who enjoy mild weather and pleasant days.
In San Sebastian in September, the total precipitation amount is 502 mm (19.8 in) spread over 29 days.
In San Sebastian in September humidity is 83%. With an average temperature of 20°C (68°F), this humidity feels like a warm, heavy blanket enveloping you, making it feel much warmer than it is. Traveling in such conditions can be quite taxing, as the air feels thick, often leading to a sense of exhaustion and requiring frequent breaks to seek shade or hydration.
In San Sebastian 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 San Sebastian, you can check here.
UV Risk Categories
Weather in San Sebastian varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in San Sebastian, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 17°C (63°F) | 13 mm (0.5 inches) | 70% | very high |
| February Weather | 19°C (66°F) | 13 mm (0.5 inches) | 65% | extreme |
| March Weather | 21°C (70°F) | 12 mm (0.5 inches) | 59% | extreme |
| April Weather | 22°C (72°F) | 3 mm (0.1 inches) | 60% | extreme |
| May Weather | 23°C (74°F) | 83 mm (3.3 inches) | 67% | extreme |
| June Weather | 21°C (70°F) | 383 mm (15.1 inches) | 80% | extreme |
| July Weather | 20°C (69°F) | 480 mm (18.9 inches) | 81% | extreme |
| August Weather | 20°C (69°F) | 557 mm (21.9 inches) | 83% | extreme |
| September Weather | 20°C (68°F) | 502 mm (19.8 inches) | 83% | extreme |
| October Weather | 20°C (68°F) | 266 mm (10.5 inches) | 80% | extreme |
| November Weather | 18°C (66°F) | 66 mm (2.6 inches) | 77% | very high |
| December Weather | 17°C (63°F) | 7 mm (0.3 inches) | 76% | very high |