Weather in Istanbul in October

How October compares

October is the 6th warmest month of the year in Istanbul and ranks 119th of 134 destinations we compare for October - see where else is hot in October. Within Turkey it is 17th of 18 (Turkey in October). Against London's average high of 14.6°C in October, Istanbul is 4.6°C warmer by day and 6.1°C warmer at night.

Daytime and night-time in October

The typical October day in Istanbul peaks at 19.2°C, but that is an average: the warmest 10% of days reach 23.2°C or more. Roughly 1 in 26 days top 25°C and 1 in 333 pass 30°C. Nights average 14.5°C; one night in ten drops to 10.6°C or lower, so pack a layer for evenings - it is genuinely cool after dark. Between 1991 and 2020 the hottest October day here reached 30.9°C (2020-10-07) and the coldest night 5.8°C (2011-10-18).

Rain in October

Wet (more than 8 rainy days): about 9 days with 1 mm or more, 78 mm in total. Year to year it varies a lot - the wettest October was 2010 with 252 mm, the driest 1993 with 4 mm. Humidity averages 76%.

Sea temperature in October

The sea averages 18.9°C - bracing (18-22°c). Depending on the year it ranges from 17.7°C to 20.2°C. For the warmest sea here, come in August (24.4°C).

Sunshine and daylight

Around 5.3 hours of sunshine a day (estimated from cloud cover), 10.9 hours of daylight: the sun rises about 07:16 and sets about 18:24 local time in mid-October. Average cloud cover is 51%.

Is October a good time to visit Istanbul?

October is not the strongest month here: mild days and frequent rain. The best months for Istanbul on our scoring are August, July, June; months averaging 25°C or more: Jul, Aug.

Comfortable days, but pack for cooler evenings

The daytime average suits being outdoors without having to organise everything around avoiding midday heat. There is still scope for a warmer afternoon: the warmest 10% of days reach at least 23.2°C. But days reaching 25°C account for just 4%, so light summer clothing alone is not a sensible packing plan. Bring layers you can remove when walking and put back on when you stop or head out in the evening. Nights average 14.5°C, with the coldest 10% falling to 10.6°C or below. A jumper and jacket are more useful than packing mainly for heat.

Leave room in your plans for rain

Rain is the main compromise in October. With about 9 rainy days, it makes sense to bring a waterproof jacket and shoes you are happy to wear on wet streets. That does not mean writing off outdoor plans, but it does favour a flexible schedule over a holiday that depends on being outside throughout. Sunshine averages about 5.3 hours within 10.9 hours of daylight, so do not mistake the available daylight for continuous sun. Use brighter spells for longer walks and keep indoor alternatives in mind. If dependable dry weather is your priority, October is a less convincing choice.

Treat swimming as an extra, not the reason to go

The sea averages 18.9°C, which puts it firmly in the bracing category rather than comfortably warm. Its October range of 18°C to 20°C also suggests that a warmer year would not turn this into a warm-water holiday. Swimming may appeal if you already enjoy cooler water, but it should not be the main reason for booking. Mild air temperatures also make having dry clothes and a warm layer ready afterwards a sensible precaution. Overall, October works better for travellers who want to spend time walking around the city, accept some rain and are happy to leave summer heat behind.