Ask anyone when to visit İstanbul and they will say spring, or September. They are not wrong. But they are answering a different question — when is the weather best — and the weather is not why you come.
December is when the city belongs to the people who live in it again. The cruise ships have gone. The queue for Hagia Sophia, an hour long in August, is a few minutes. Topkapı’s courtyards, which in summer feel like a railway station, are quiet enough to hear the fountains. The Grand Bazaar’s shopkeepers have time to pour you tea and mean it.
Cold, but built for it
We will not pretend it is warm. Days run between roughly six and eleven degrees, a damp cold rather than a dry one, and rain is likely at some point in the week. So a good December programme is built the way the city itself is built — around covered places.
In August you would wait an hour for Hagia Sophia. In December you walk in.
Palaces and museums sit in the middle of the day, when the light is worth going out for. The Grand Bazaar, the Spice Bazaar and the arcades of İstiklal take the late afternoon, which ends early: the sun sets around a quarter to five. Dinner starts when it is dark, and long.
What you actually see
The Blue Mosque, the Hippodrome and the Basilica Cistern are a ten-minute walk from each other and from Hagia Sophia. Topkapı, the Harem and Hagia Irene share a courtyard. Balat and Fener are a morning; Ortaköy, Çamlıca Hill and Üsküdar are an afternoon that ends with tea and a view back at Europe.
None of that changes with the season. What changes is whether you are looking at the dome or at the back of someone’s head.
The short answer
If you want the Bosphorus at its bluest, come in May. If you want the city — the actual, working, two-thousand-year-old city — come when everyone else has gone home. That is December, and it is why we run a small-group programme there in the second half of the month.