WEATHER · CLIMATE NORMALS · 1991–2020
Istanbul Climate — Averages by Month
What the weather in Istanbul, TRaverages across a standard 30-year period. Each month's figure is the 1991–2020 mean temperature and total rainfall from the ERA5 reanalysis — the long-run normal a place settles around, not a forecast for any particular day.
Month-by-month normals
| Month | Avg temperature | Avg rainfall |
|---|---|---|
| January | 6.4 °C · coldest | 90.7 mm |
| February | 6.6 °C | 75.8 mm |
| March | 8.3 °C | 76.9 mm |
| April | 11.8 °C | 50.7 mm |
| May | 16.7 °C | 38.1 mm |
| June | 21.6 °C | 35.5 mm |
| July | 24.0 °C | 26.4 mm |
| August | 24.4 °C · warmest | 24.2 mm |
| September | 21.1 °C | 50.2 mm |
| October | 16.8 °C | 80.3 mm |
| November | 12.3 °C | 77.2 mm |
| December | 8.5 °C | 104.8 mm · wettest |
How to read these numbers
These are reanalysis normals, not readings from a single weather station. They come from the ERA5 0.25° (~25 km) global reanalysis grid, sampled at the grid cell nearest Istanbul — centred at 41.00°N, 29.00°E. A reanalysis blends observations with a physics model onto an even grid, so a coastal or mountain city's cell can read a little cooler, warmer, wetter or drier than the city centre itself. The month-to-month shape — when it's hot, when it rains — is what these normals capture best.
“Normal” means the 1991–2020 average, the current World Meteorological Organization standard period. A normal is what a place tends toward over decades — any single day, month or year can and will depart from it.