Quick answer: Rain risk in Istanbul is answered hour by hour above: below 20 % probability plans are safe, 20–50 % means carry a jacket, and above 50 % expect to get wet. Forecast confidence is highest inside 72 hours.
Conditions on this page are recalculated from the latest forecast every time it is opened, for the current date in the location's own time zone.
A direct rain answer for Istanbul: how many of the next 24 hours are wet, when the first and last rain arrive, the heaviest hour, the longest dry window, and each of the next seven days with its maximum rain chance and expected amount. Every value is the live Open-Meteo forecast loaded when the page opens; probability is a model estimate, not a guarantee.
Probability alone is not a decision. In Istanbul we treat under 20 % as go, 20–50 % as carry-a-layer, and over 50 % as plan indoors — and we pair every figure with expected millimetres, because 60 % chance of 0.3 mm drizzle is a completely different day from 40 % chance of 12 mm. A confidence band based on forecast lead time is shown so you know how much the timing could still shift.
Daylight, midday sun angle and golden-hour length below are calculated for Istanbul's own coordinates (41.01° N, 28.98° E) on the 15th of each month. These are solar geometry, not climate averages.
| Month | Daylight | Sun at solar noon | Golden hour |
|---|---|---|---|
| January | 9 h 30 min | 28° | 61 min |
| February | 10 h 36 min | 36° | 56 min |
| March | 11 h 48 min | 46° | 53 min |
| April | 13 h 18 min | 58° | 54 min |
| May | 14 h 30 min | 68° | 58 min |
| June | 15 h 6 min | 72° | 62 min |
| July | 14 h 48 min | 71° | 60 min |
| August | 13 h 48 min | 63° | 56 min |
| September | 12 h 24 min | 51° | 53 min |
| October | 11 h 0 min | 39° | 55 min |
| November | 9 h 48 min | 30° | 60 min |
| December | 9 h 12 min | 26° | 63 min |
Scores are capped by dealbreakers — heavy rain, dangerous wind, thick fog or hazardous UV pull a day down no matter how pleasant the rest of the numbers look. Forecast data is Open-Meteo; solar and lunar values are computed for Istanbul's own coordinates and time zone. Full details on the methodology page.