Weather in Istanbul in December

How December compares

December is the 10th warmest month of the year in Istanbul and ranks 119th of 134 destinations we compare for December - see where else is hot in December. Within Turkey it is 18th of 18 (Turkey in December). Against London's average high of 7.7°C in December, Istanbul is 2.5°C warmer by day and 3.6°C warmer at night.

Daytime and night-time in December

The typical December day in Istanbul peaks at 10.2°C, but that is an average: the warmest 10% of days reach 14.7°C or more. Days over 25°C are rare. Nights average 6.3°C; one night in ten drops to 2.0°C or lower, so pack a layer for evenings - it is genuinely cool after dark. Between 1991 and 2020 the hottest December day here reached 21.4°C (2010-12-02) and the coldest night -1.8°C (1992-12-30).

Rain in December

Wet (more than 8 rainy days): about 13 days with 1 mm or more, 97 mm in total. Year to year it varies a lot - the wettest December was 2001 with 236 mm, the driest 2015 with 26 mm. Humidity averages 78%.

Sea temperature in December

The sea averages 11.1°C - too cold for most (under 18°c). Depending on the year it ranges from 9.6°C to 12.3°C. For the warmest sea here, come in August (24.4°C).

Sunshine and daylight

Around 3.0 hours of sunshine a day (estimated from cloud cover), 9.1 hours of daylight: the sun rises about 08:22 and sets about 17:37 local time in mid-December. Average cloud cover is 67%.

Is December a good time to visit Istanbul?

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

Cool days, with colder evenings to plan for

A proper coat and layers make more sense than a light jacket alone. The average daytime high is comfortable enough for walking if you dress warmly, but sitting outside is a less appealing prospect. Milder days can reach around 15°C, although that is not the temperature to build your packing around. At the colder end, nights can fall to 2°C or below, so bring a warm layer for returning late. Midday is the sensible window for longer outdoor stretches; evenings call for warmer clothing. December suits travellers who prefer cool conditions to heat, provided they are not expecting reliably mild weather.

Keep outdoor plans flexible

Rain is the main catch: about 13 days have measurable rainfall, so waterproof outerwear and shoes that cope with wet pavements deserve space in your bag. That does not mean every day is a washout, but a rigid outdoor itinerary is a poor fit. Keep indoor options available and use dry spells when they arrive. There are about 9.1 hours of daylight, with around 3 hours of sunshine, so plan daylight-dependent activities before evening rather than leaving them until late. A slow start uses up a meaningful part of the available light. Go with flexible expectations and December can work; choose another month if long, sunny days matter most.