Istanbul Weather in September
Turkey · Mediterranean climate · Data averaged from 2020-01-01 to 2024-12-31 (5 years)
September in Istanbul sees average temperatures ranging from a low of 18.0°C (64.4°F) to a high of 25.9°C (78.6°F), with a mean of 21.5°C (70.7°F). Compared to the annual average of 15.3°C (59.5°F), this month is 6.2°C warmer than the yearly norm. Precipitation averages 47.0mm, making it approximately 17.0mm drier than the monthly average of 64.0mm. The city receives an average of 11.0 hours of sunshine per day during September, with relative humidity averaging 71.3%. Wind speeds reach an average maximum of 22.4 km/h. For travelers, this month offers a temperature experience in Istanbul, with drier-than-average conditions compared to the rest of the year.
Istanbul is a city where you can wake up sweating and need a jacket by sunset. I packed for August heat once and froze on a Bosphorus ferry at 9pm. Layers are essential — even summer evenings dip to 19°C with wind off the water. Pack a scarf (useful for mosques anyway). My favorite window is late September to October: 22°C, low humidity, fewer tourists at the Hagia Sophia. Skip February — cold rain, grey skies, many outdoor cafés shuttered. April brings tulip season and the city reawakens.
September vs Adjacent Months
| Metric | August | September | October |
|---|---|---|---|
| Mean Temp | 25.2°C (77.4°F) | 21.5°C (70.7°F) | 16.9°C (62.4°F) |
| Rainfall | 19.7mm | 47.0mm | 44.1mm |
| Sunshine | 12.6 hrs | 11.0 hrs | 8.6 hrs |
| Humidity | 70.8% | 71.3% | 76.6% |
| Wind | 23.9 km/h | 22.4 km/h | 20.5 km/h |
| Rainy Days | 8.0 | 12.8 | 11.6 |
Seasonal Context
September falls in Autumn in the Northern Hemisphere. Autumn sees temperatures gradually cooling from summer highs. For travelers visiting Istanbul in September, the data indicates favorable conditions based on the combination of temperature, precipitation, and daylight hours.
Frequently Asked Questions
What is the average temperature in Istanbul in September?
The average temperature in Istanbul during September ranges from 18.0°C (64.4°F) to 25.9°C (78.6°F), with a mean of 21.5°C (70.7°F).
How much does it rain in Istanbul in September?
Istanbul receives an average of 47.0mm of precipitation in September, spread across approximately 12.8 rainy days.
What should I pack for Istanbul in September?
Based on September weather data, pack layers including light jackets and t-shirts, plus an umbrella.
Is September a good time to visit Istanbul?
September is a good time to visit Istanbul, with comfortable temperatures and manageable rainfall.
Other Months for Istanbul
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: 41.01°, 28.98°. Timezone: Europe/Istanbul. Last updated: 2026-07-30.