Istanbul → Paris Turbulence Forecast

Istanbul to Paris is about 2,219 km and usually takes around 3h 30m in the air. The track it follows runs over the Balkans, the Alps, Central Europe, and Western Europe.

Air lifting over the Alps can raise brief, light ripples at cruise; crews know these spots well and the movement stays gentle. Over the Balkans, Central Europe, and Western Europe the air is usually calm and settled. This track threads jet-stream latitudes, so in winter you may feel a few minutes of light, choppy air high up; summer usually rides calmer.

For most of a flight this length you are at a steady cruise above the weather, where the ride is smooth; the livelier moments, if any, are short.