Everything you need to know about Istanbul's weather and climate. From seasonal temperature patterns and rainfall data to humidity levels and what to pack for every season — your complete weather planning guide for visiting Turkey's largest city.
Understanding Istanbul's Climate
Istanbul sits at a unique geographical crossroads — straddling two continents and bordered by the Sea of Marmara, the Bosphorus strait, and the Black Sea. This positioning gives the city a transitional climate that blends Mediterranean and oceanic influences, resulting in warm, humid summers and cool, wet winters. Understanding these weather patterns is essential for planning a comfortable and enjoyable visit.
The city's climate is classified as borderline Mediterranean and humid subtropical. Unlike cities further south along the Turkish coast such as Antalya, Istanbul experiences genuine winter cold and significant rainfall from November through March. For real-time conditions, always check the live Istanbul 16-day forecast before your trip.
Temperature Patterns Throughout the Year
Winter Temperatures (December–February)
Istanbul's winters are genuinely cold, though rarely extreme. Average daytime highs range from 8°C to 10°C, while nighttime lows can drop to 2°C to 4°C. January is typically the coldest month, and temperatures occasionally dip below freezing. Snow falls on average three to five times per winter, though it rarely accumulates for more than a day or two. The wind chill factor from Bosphorus winds can make it feel significantly colder than the thermometer reads, particularly along the waterfront.
Spring Temperatures (March–May)
Spring brings a gradual warming trend. March starts cool at 7°C to 12°C, April warms to 10°C to 17°C, and by May temperatures reach a very pleasant 14°C to 22°C. Spring weather can be changeable, with warm sunny days interrupted by cool, rainy spells. The temperature difference between morning and afternoon can be as much as 10°C, making layers essential during this season.
Summer Temperatures (June–August)
Summers in Istanbul are warm to hot. June averages 19°C to 27°C, July peaks at 22°C to 30°C (occasionally reaching 35°C during heat waves), and August remains similarly warm at 22°C to 29°C. The combination of heat and humidity can make July and August feel quite oppressive, particularly in densely built-up areas away from the water. Sea breezes along the Bosphorus provide welcome relief.
Autumn Temperatures (September–November)
Autumn is a beautiful transitional season. September remains warm at 18°C to 26°C, October cools to 13°C to 20°C, and November drops to 8°C to 14°C. Early autumn feels like an extension of summer, while late November can feel firmly wintry. The cooling trend accelerates through the season, and the first significant cold snaps typically arrive in mid-November.
Rainfall and Precipitation
Istanbul receives approximately 800 to 850 mm of rainfall annually, distributed unevenly across the seasons. The wettest months are November, December, and January, each receiving 90 to 110 mm of rain. Summer is the driest period, with July averaging only 20 to 30 mm. However, summer thunderstorms can occur without much warning, delivering short but heavy downpours.
Rain patterns differ between seasons. Winter rain tends to be persistent and drizzly, sometimes lasting for days. Spring showers are typically brief and followed by sunshine. Summer storms are intense but short-lived, often clearing within an hour. Autumn rain increases gradually, with October and November transitioning back to the persistent winter pattern.
The Black Sea side of Istanbul (northern districts) generally receives more rainfall than the Marmara coast (southern districts). You can check conditions across different areas using the Istanbul district weather overview.
Humidity and Wind
Humidity is a significant factor in Istanbul's weather comfort. Average relative humidity ranges from 70% to 80% year-round, with winter months being the most humid. In summer, the combination of temperatures above 30°C and humidity above 60% can create uncomfortably muggy conditions, particularly in July and August.
Wind is another important consideration, especially for Bosphorus activities. The prevailing wind direction is from the northeast (known locally as "poyraz"), bringing cool, sometimes harsh conditions in winter. The southwesterly "lodos" wind brings warmer, wetter weather. Wind speeds average 10 to 20 km/h, but gusts along the Bosphorus can exceed 40 km/h during storms. Before booking a Bosphorus cruise, check the wind forecast — calm conditions under 15 km/h provide the most comfortable experience.
Sunshine Hours
Istanbul enjoys generous sunshine in summer, averaging 10 to 12 hours of direct sunlight per day in June and July. Winter is considerably gloomier, with only 2 to 4 hours of sunshine daily in December and January. Overcast skies are common from November through February, giving the city its characteristic winter atmosphere of grey skies and misty waterways.
Daylight hours range from approximately 9 hours in late December to over 15 hours in late June. Check the Istanbul sunrise and sunset times to plan your photography sessions and outdoor activities around golden hour.
What to Pack: Season by Season
Winter Packing List (December–February)
Istanbul winters demand serious warm clothing. Pack a heavy winter coat or down jacket, as temperatures frequently hover around 5°C with biting winds. Thermal base layers are highly recommended for January visits. Waterproof boots with good grip are essential, as cobblestone streets become slippery when wet. Bring a warm hat, scarf, and gloves — the wind chill along the Bosphorus can be brutal. A compact but sturdy umbrella is crucial, as rain is frequent. Despite the cold, you will be entering heated mosques and shops frequently, so dress in layers you can easily remove.
Spring Packing List (March–May)
Spring is all about versatile layering. Bring a medium-weight jacket or fleece, a light waterproof layer, and several long-sleeve shirts you can combine. Comfortable walking shoes with good support are essential — Istanbul's hills and cobblestones demand proper footwear. A compact umbrella or rain jacket is important, especially in March and early April. By May, you can include lighter clothing, but always carry a sweater for cooler evenings. Sunglasses become useful from April onward.
Summer Packing List (June–August)
Light, breathable fabrics are essential for Istanbul's hot, humid summers. Cotton and linen are ideal. Pack sunscreen (SPF 30 or higher), a hat with a brim, and quality sunglasses. A reusable water bottle is important for staying hydrated during long days of sightseeing. Always carry a light scarf or shawl for mosque visits — women will need head covering, and both men and women should be able to cover shoulders and knees. Despite the heat, pack one light sweater for aggressively air-conditioned restaurants and museums. Comfortable, breathable sandals or walking shoes are preferable to heavy boots.
Autumn Packing List (September–November)
Autumn packing resembles spring but with a slightly warmer focus in September and a cooler one in November. For September, summer clothing with a light jacket will suffice. October requires medium layers similar to spring. By November, you should pack almost as warmly as winter — a warm coat, waterproof layers, and closed-toe waterproof shoes. An umbrella becomes essential from mid-October onward. Layering remains the key strategy, as autumn days can start cool, warm up significantly by midday, and cool again rapidly after sunset.
Special Weather Considerations
The Bosphorus Effect
The Bosphorus strait creates its own microclimate. Temperatures along the waterfront can be 2 to 3 degrees cooler than inland areas in summer (a welcome relief) and feel considerably colder in winter due to wind exposure. Morning fog over the Bosphorus is common in autumn and winter, sometimes delaying ferry services. This fog typically burns off by mid-morning.
Urban Heat Island
Central Istanbul, particularly densely built neighborhoods like Fatih and Eminönü, can be several degrees warmer than outlying districts. In summer, the concrete and asphalt absorb and radiate heat, making midday temperatures feel oppressive. The parks and waterfront areas offer the most comfortable conditions on hot days.
Earthquake Awareness
While not a weather phenomenon, Istanbul sits in a seismically active zone. Turkey's weather and alert page includes relevant warnings. Familiarize yourself with earthquake safety procedures before visiting, and note the emergency exits in your hotel.
Comparing Istanbul's Weather to Other Destinations
Istanbul's climate sits somewhere between Mediterranean and northern European. It is warmer than London year-round but cooler and wetter than cities on Turkey's southern coast like Antalya. In summer, Istanbul is comparable to Barcelona or Athens in temperature, though more humid. In winter, it is milder than central European cities like Berlin or Vienna but considerably colder and wetter than destinations like Dubai.
If Istanbul's winter weather seems too challenging, the Turkish Riviera around Antalya offers mild winters with daytime temperatures around 15°C. For summer escapes from Istanbul's heat, the Cappadocia region around Göreme sits at a higher elevation and offers cooler, drier conditions.
Planning with Real-Time Weather Data
No weather guide can predict exact conditions weeks or months in advance. For the most accurate trip planning, we recommend checking the Istanbul 16-day forecast two weeks before your departure and again a few days before traveling. The forecast provides hourly breakdowns of temperature, precipitation probability, wind speed, and humidity — everything you need to plan each day of your visit.
You can also check the current local time in Istanbul and geographic details including sunrise and sunset times to fine-tune your daily schedule. Istanbul's weather may be unpredictable, but with the right preparation, every season offers its own unforgettable experience.
