Weather in Istanbul in September 2025
Average weather
Average temperature in Istanbul in September
Going from a maximum of +29°C during the day to a minimum of +17°C during the night, the temperature in September averages around +26°C.
The average maximum temperature goes down 42% by the end of the month, compared with the beginning of the month, from +28°C to +23°C.
Is Istanbul warm or cold in September?
Istanbul is typically warm in September.
Maximum temperatures go down compared to the previous month from +28°C to +24°C. The minimum temperature also goes down from +22°C to +19°C.
It’s generally warm, but pack a long-sleeve shirt for evenings.
Take a look at how September is compared to other months in Istanbul:
Water temperature in Istanbul in September
Water in Istanbul in September is Comfortable. It varies from +21°C to +25°C, with an average of +23°C. This is almost similar to the air temperature, which averages +24°C.
The water temperature in September is one of the warmest of the entire year:
Can you swim in Istanbul in September?
Climate in Istanbul in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +28°C | +24°C | +19°C | ||||
| Min. temperature | ||||||
| +16°C | +12°C | +5°C | ||||
| Max. temperature | ||||||
| +35°C | +36°C | +31°C | ||||
| Rainfall | ||||||
| 14 mm | 31 mm | 57 mm | ||||
| Wind | ||||||
| 4 m/s | 3 m/s | 3 m/s | ||||
| Avg. water temperature | ||||||
| +25°C | +23°C | +19°C | ||||
| Humidity | ||||||
| 66% | 67% | 73% | ||||
| Air pressure | ||||||
| 1012 HPa | 1015 HPa | 1018 HPa | ||||
| Sunny days | ||||||
| 22 | 17 | 12 | ||||
| Cloudy days | ||||||
| 3 | 5 | 8 | ||||
| Rainy days | ||||||
| 5 | 6 | 10 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September weather is still as great as in August. It’s getting colder in September. From +28°C in the day, the average maximum temperature lowers to +24°C. Prepare for more rain. Average rainfall goes from 14 mm to 31 mm. Humidity rises from 66% to 67%. Winds are calmer in comparison to August, going down from 4 m/s to 3 m/s on average. The days becoming less sunny, going from 22 sunny days in August to 17 in September.
Next month (October) brings a further decline in the weather.
Wind
The average wind speed is 5 m/s getting up to 8 m/s which is a medium breeze. You can feel it, especially getting out of the water.
The average wind speed in Istanbul is gradually decreasing during September, going from 4 m/s to 2 m/s over the course of the month.
Rain
How was the weather last September in Istanbul?
Climate Change over Years
The climate in Istanbul in September has not changed much over the last 43 years.
The average temperature was the lowest in 1997 (+16°C) and the highest in 2019 (+20°C). The driest year was 1984 with only 361 mm of rainfall, and the wettest year was 2010 with 859 mm.
FAQ
Is September a good time to visit Istanbul?
Can you sunbathe in Istanbul in September?
Can you swim in Istanbul in September?
Is Istanbul rainy in September?
Is it sunny in Istanbul in September?
Other cities in Turkey
Monthly weather in Istanbul
Source of the data
For this page, we’ve looked at the typical weather in Istanbul, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.