Santiago Weather in September
Chile · Mediterranean climate · Data averaged from 2020-01-01 to 2024-12-31 (5 years)
September in Santiago sees average temperatures ranging from a low of 8.5°C (47.3°F) to a high of 18.4°C (65.1°F), with a mean of 12.7°C (54.9°F). Compared to the annual average of 16.1°C (61.0°F), this month is 3.4°C cooler than the yearly norm. Precipitation averages 31.4mm, making it approximately 1.0mm wetter than the monthly average of 30.0mm. The city receives an average of 9.0 hours of sunshine per day during September, with relative humidity averaging 69.9%. Wind speeds reach an average maximum of 12.8 km/h. For travelers, this month offers a temperature experience in Santiago, with wetter-than-average conditions compared to the rest of the year.
Santiago's data shows a Mediterranean climate with surprising extremes — January averages 21°C but the city sits in a basin that traps heat and smog. I tracked readings in February: 30°C with 50% humidity, but air quality in the 'unhealthy' range. The numbers favor September-November: 15-19°C, low rain, clearer air. December-March is hot and dry with smog issues. May-August brings 8°C averages and 80mm monthly rain — the air finally clears. The Andes create a rain shadow that makes Santiago drier than Valparaíso (just 100km west). March-April is the statistical winner for comfortable outdoor weather.
September vs Adjacent Months
| Metric | August | September | October |
|---|---|---|---|
| Mean Temp | 11.1°C (52.0°F) | 12.7°C (54.9°F) | 15.5°C (59.9°F) |
| Rainfall | 77.1mm | 31.4mm | 15.9mm |
| Sunshine | 8.2 hrs | 9.0 hrs | 11.3 hrs |
| Humidity | 69.6% | 69.9% | 62.1% |
| Wind | 11.0 km/h | 12.8 km/h | 15.7 km/h |
| Rainy Days | 10.6 | 9.4 | 5.2 |
| Snowfall | 0.5 cm | 0.0 cm | 0.0 cm |
Seasonal Context
September falls in Autumn in the Northern Hemisphere. Autumn sees temperatures gradually cooling from summer highs. For travelers visiting Santiago in September, the data indicates mixed conditions based on the combination of temperature, precipitation, and daylight hours.
Frequently Asked Questions
What is the average temperature in Santiago in September?
The average temperature in Santiago during September ranges from 8.5°C (47.3°F) to 18.4°C (65.1°F), with a mean of 12.7°C (54.9°F).
How much does it rain in Santiago in September?
Santiago receives an average of 31.4mm of precipitation in September, spread across approximately 9.4 rainy days.
What should I pack for Santiago in September?
Based on September weather data, pack warm layers, a medium jacket, and waterproof outerwear.
Is September a good time to visit Santiago?
September is a cooler month, suitable for travelers who prefer mild weather and fewer crowds. Pack warm layers and enjoy indoor attractions.
Other Months for Santiago
Cities with Similar September Climate (Mediterranean)
Data Source: Open-Meteo historical archive (2020-01-01 to 2024-12-31). Daily measurements aggregated into monthly climate normals. Coordinates: -33.45°, -70.67°. Timezone: America/Santiago. Last updated: 2026-07-30.