Istanbul in August is as hot as July, with average highs of 29.7°C (86°F), and it has the warmest sea of the year, about 24.2°C on average in the Sea of Marmara. It stays dry, with about 3.6 rainy days. Istanbul received 1,852,996 foreign visitors in August 2025. 30 August is a public holiday.
Checked on 10 November 2026. Climate: MGM (1950–2025). Sea: MGM Marmara sea report. Visitor figures: the provincial tourism directorate, July 2026 edition. Daylight hours are our own 2027 estimate. August 2026 visitor numbers were not out when we checked.
Istanbul in August: weather, sea and daylight
| Long-term average | August |
|---|---|
| Daytime high | 29.7°C (85°F) |
| Night low | 20.8°C (69°F) |
| Rainy days | 3.6 |
| Monthly rain | 23.9 mm |
| Warmest day on record | 40.1°C (104°F) |
| Coldest day on record | 14.3°C (58°F) |
| Sea of Marmara, average water temperature | 24.2°C (76°F) |
The water figure is the 1970–2025 monthly average for the whole Sea of Marmara, not for the Bosphorus or the Black Sea beaches, so a local beach can feel colder.
Daylight falls through the month. On 1 August 2027 the sun rises near 05:59 and sets near 20:22. By 15 August it rises near 06:13 and sets near 20:05, giving 13h52m of daylight. The evenings are still long, but each week ends a little earlier.
Istanbul in August: daylight through the month
| 2027 | Sunrise | Sunset | Daylight |
|---|---|---|---|
| 1 Aug | 05:59 | 20:22 | 14h23m |
| 15 Aug | 06:13 | 20:05 | 13h52m |
| 31 Aug | 06:29 | 19:41 | 13h12m |
August loses about 1 hour 11 minutes of daylight, and the sun sets before 20:00 from about 20 August.
The sea peaks in August
| Sea of Marmara average | May | June | July | August | September | October |
|---|---|---|---|---|---|---|
| Water temperature | 15.4°C | 20.2°C | 23.4°C | 24.2°C | 22.3°C | 18.8°C |
The MGM series puts August as the warmest month for the water. The figure is a Marmara average for 1970 to 2025, so Bosphorus and Black Sea beaches can differ.
30 August: Victory Day
30 August is Victory Day in Türkiye, a public holiday. Expect flags, ceremonies and a day off for many locals. Check the opening days for any museum you plan to visit, and read our closing days guide. In 2027 it falls on a Monday, so some people will take a long weekend.
How busy is Istanbul in August?
| Foreign visitors to Istanbul | Number |
|---|---|
| August 2024 | 1,802,290 |
| August 2025 | 1,852,996 (+2.8% on 2024) |
August is, with July, the busiest stretch of the year. In 2025 it drew about 1.85 million visitors, close to October’s 1.86 million. Book popular timed tickets early, as our official tickets guide explains.
Where to cool down in August
- Ferries and the Bosphorus. The breeze helps. See our Bosphorus cruise guide.
- The Princes’ Islands. Cars are largely banned on the islands, and you can swim from some beaches. See our Büyükada vs Heybeliada guide.
- Museums and cisterns. They are cool inside. See our Basilica Cistern guide.
- Hammams. A steam bath in August is not for everyone, so read our hammam guide first.
Per day, the official count gives about 59,770 foreign arrivals in August 2025. That is slightly below July 2026 at about 62,320 a day, though the two figures come from different years. Treat them as a rough guide only.
An August day that avoids the worst heat
Begin with a ferry at 08:00, when the breeze is cool. Visit one indoor sight at midday, such as a museum or the cistern. Return to the water after 17:00. If you cannot face a full day, take the Princes’ Islands ferry and plan your swim around the shade. See our travel costs guide to budget for peak-season prices.
Packing list for an August trip
- Light cotton clothing and a scarf for mosques.
- A hat, sunglasses and sun cream.
- A water bottle, plus electrolyte sachets for long walks.
- Swimwear and a quick-dry towel.
Should you visit Istanbul in August?
It works for swimming and warm nights. It works less well if you dislike midday heat or crowds. Our weather table compares it with the rest of the year.
August questions answered
Which month is hottest?
July and August tie at a 29.7°C average high, and August has the warmest sea.
Is 30 August a holiday?
Yes. Victory Day is a public holiday.
