Istanbul or London: which climate?
Istanbul (Republic of Türkiye) has a hot-summer mediterranean climate, whereas London (United Kingdom) has a temperate oceanic climate, according to the Köppen-Geiger classification.
The values compared here are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme. The same method and the same period apply to Istanbul and to London.
Istanbul is warmer than London by 4.3 °C in annual average: 14.5 °C against 10.2 °C.
Istanbul gets more rain than London: 697 mm per year against 615 mm.
Istanbul gets 9.5 hours of sunshine per day on average, against 7.5 hours in London.
Istanbul and London are warming at the same rate: about +1.6 °C between 1940 and 2025 on both sides.
Istanbul averages 3 hot days (≥ 30 °C) and 5 frost days per year; London averages 1 and 36.
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
| Indicator | Istanbul | London | Difference |
|---|---|---|---|
| Mean daily temperature | 14.5 °C | 10.2 °C | -4.3 °C |
| Average daily high | 16.8 °C | 13.4 °C | -3.4 °C |
| Average daily low | 12.5 °C | 6.9 °C | -5.6 °C |
| Annual rainfall | 697 mm | 615 mm | -82 mm |
| Sunshine / day | 9.5 h | 7.5 h | -2.0 h |
| Hot days (≥ 30 °C) | 3 d/yr | 1 d/yr | negligible |
| Frost days (< 0 °C) | 5 d/yr | 36 d/yr | +31 d/yr |
| Rainy days (≥ 1 mm) | 105 d/yr | 123 d/yr | +18 d/yr |
| Mean relative humidity | 76 % | 80 % | +4 % |
| Average peak wind | 21.4 km/h | 20.4 km/h | negligible |
A difference is only reported when it exceeds the resolution of the data. ERA5 is a reanalysis on a grid of about 31 km: two nearby cities often fall in the same cell, and below half a degree you are reading the grid, not the climate.