Istanbul Weather by Month – Temperature, Sea & Rain

Istanbul weather by month from 10 years of data: 9°C by day in January, 29°C in August, sea up to 25°C. Rain, daylight and the best time to visit.

Istanbul sits on the Bosphorus between the Black Sea and the Sea of Marmara and has four distinct seasons. Summers are warm and humid, winters are cool, grey and often rainy, and spring and autumn are the most pleasant times for sightseeing.

Istanbul climate at a glance

Hottest month: August (29°C by day)
Coldest month: January (9°C by day, 4°C at night)
Swimming season: July to September (sea 22°C or warmer); warmest sea in August at about 25°C
Wettest month: January (109 mm); yearly total about 755 mm

Istanbul climate table

Month	Day / night	Sea	Rain mm (days)	Daylight
January	9° / 4°	10°	109 (13)	9.6 h
February	11° / 5°	9°	77 (11)	10.6 h
March	12° / 5°	10°	77 (11)	12.0 h
April	17° / 9°	12°	56 (9)	13.3 h
May	21° / 13°	16°	57 (8)	14.5 h
June	26° / 18°	21°	51 (8)	15.1 h
July	29° / 21°	24°	31 (5)	14.8 h
August	29° / 22°	25°	20 (3)	13.8 h
September	26° / 18°	23°	48 (8)	12.5 h
October	20° / 14°	20°	55 (7)	11.1 h
November	16° / 10°	16°	84 (9)	9.9 h
December	11° / 6°	13°	90 (12)	9.3 h

Day / night: average daily maximum / minimum air temperature (°C). Sea: average sea surface temperature off the coast. Rain: monthly total; in brackets, days with at least 1 mm of rain.

Best time to visit Istanbul

Beach holiday: July to August, when the air is warm and the sea is 22°C or warmer.
Sightseeing and active holidays: April to June and September to November – pleasant temperatures and few rainy days.
Quiet season: December to February – the coolest and wettest time, with fewer visitors and lower prices.

Snow falls on a few days in most winters, usually in January or February, and can briefly slow down traffic to and from the airports – allow extra time.

Istanbul weather month by month

Istanbul weather in January: 9°C / 4°C

Istanbul averages 9°C during the day and 4°C at night in January. The sea is cool at around 10°C, so most visitors swim in heated indoor pools. This is one of the wetter months, with about 13 rainy days and 109 mm of rain – pack a rain jacket. Pack a warm jacket, a sweater and waterproof shoes. Daylight lasts about 9.6 hours.

Istanbul weather in February: 11°C / 5°C

Istanbul averages 11°C during the day and 5°C at night in February. The sea is cool at around 9°C, so most visitors swim in heated indoor pools. This is one of the wetter months, with about 11 rainy days and 77 mm of rain – pack a rain jacket. Pack a warm jacket, a sweater and waterproof shoes. Daylight lasts about 10.6 hours.

Istanbul weather in March: 12°C / 5°C

Istanbul averages 12°C during the day and 5°C at night in March. The sea is cool at around 10°C, so most visitors swim in heated indoor pools. This is one of the wetter months, with about 11 rainy days and 77 mm of rain – pack a rain jacket. Pack a warm jacket, a sweater and waterproof shoes. Daylight lasts about 12.0 hours.

Istanbul weather in April: 17°C / 9°C

Istanbul averages 17°C during the day and 9°C at night in April. The sea is cool at around 12°C, so most visitors swim in heated indoor pools. This is one of the wetter months, with about 9 rainy days and 56 mm of rain – pack a rain jacket. Bring layers: T-shirt weather on sunny afternoons, a sweater or light jacket in the evening. Daylight lasts about 13.3 hours.

April is tulip season: the Istanbul Tulip Festival fills Emirgan Park and other parks with millions of flowers.

Istanbul weather in May: 21°C / 13°C

Istanbul averages 21°C during the day and 13°C at night in May. The sea is cool at around 16°C, so most visitors swim in heated indoor pools. This is one of the wetter months, with about 8 rainy days and 57 mm of rain – pack a rain jacket. Bring layers: T-shirt weather on sunny afternoons, a sweater or light jacket in the evening. Daylight lasts about 14.5 hours.

Istanbul weather in June: 26°C / 18°C

Istanbul averages 26°C during the day and 18°C at night in June. The sea is refreshing at around 21°C – fine for a quick swim on sunny days. This is one of the wetter months, with about 8 rainy days and 51 mm of rain – pack a rain jacket. Summer clothes are fine during the day; a light layer is handy for the evening. Daylight lasts about 15.1 hours.

Istanbul weather in July: 29°C / 21°C

Istanbul averages 29°C during the day and 21°C at night in July. At around 24°C, the sea is pleasant for swimming. Expect around 5 rainy days (31 mm), mostly short showers. Summer clothes are fine during the day; a light layer is handy for the evening. Daylight lasts about 14.8 hours.

For a swim, locals head to the Black Sea beaches at Kilyos or to the Princes' Islands in the Sea of Marmara.

Istanbul weather in August: 29°C / 22°C

Istanbul averages 29°C during the day and 22°C at night in August. At around 25°C, the sea is pleasant for swimming. There are only about 3 rainy days in the month. Summer clothes are fine during the day; a light layer is handy for the evening. Daylight lasts about 13.8 hours.

Istanbul weather in September: 26°C / 18°C

Istanbul averages 26°C during the day and 18°C at night in September. At around 23°C, the sea is pleasant for swimming. Expect around 8 rainy days (48 mm), mostly short showers. Summer clothes are fine during the day; a light layer is handy for the evening. Daylight lasts about 12.5 hours.

Istanbul weather in October: 20°C / 14°C

Istanbul averages 20°C during the day and 14°C at night in October. The sea is cool at around 20°C, so most visitors swim in heated indoor pools. Expect around 7 rainy days (55 mm), mostly short showers. Bring layers: T-shirt weather on sunny afternoons, a sweater or light jacket in the evening. Daylight lasts about 11.1 hours.

Istanbul weather in November: 16°C / 10°C

Istanbul averages 16°C during the day and 10°C at night in November. The sea is cool at around 16°C, so most visitors swim in heated indoor pools. This is one of the wetter months, with about 9 rainy days and 84 mm of rain – pack a rain jacket. Bring layers: T-shirt weather on sunny afternoons, a sweater or light jacket in the evening. Daylight lasts about 9.9 hours.

Istanbul weather in December: 11°C / 6°C

Istanbul averages 11°C during the day and 6°C at night in December. The sea is cool at around 13°C, so most visitors swim in heated indoor pools. This is one of the wetter months, with about 12 rainy days and 90 mm of rain – pack a rain jacket. Pack a warm jacket, a sweater and waterproof shoes. Daylight lasts about 9.3 hours.

Getting to Istanbul

The nearest airports for Istanbul are Istanbul Airport (IST) and Sabiha Gökçen Airport (SAW). 4 Seasons Transfer offers private airport transfers at a fixed price per vehicle, with air-conditioned cars, flight tracking and meet & greet – whatever the weather.

Frequently asked questions

When is the best time to visit Istanbul?
For a beach holiday, July to August is ideal. For sightseeing and hiking, choose April to June and September to November, when it is warm but not hot.

When is the sea warm enough to swim in Istanbul?
The sea is 22°C or warmer from July to September. It is warmest in August, at about 25°C.

What is the hottest month in Istanbul?
August, with an average daytime high of 29°C and nights around 22°C.

What is the weather like in Istanbul in winter?
From December to February days average about 10°C and nights about 5°C. Expect around 37 rainy days over the three months, with plenty of sunny days in between.

Weather in other destinations

Source: averages for 2015–2024 calculated by 4 Seasons Transfer. Air temperature, rain and daylight: ERA5 reanalysis (Copernicus / ECMWF) via Open-Meteo, licence CC BY 4.0. Sea temperature: NOAA OISST v2.1 monthly means (NOAA PSL). The weather in a given year can differ from these averages.