Athens or Porto: which climate?
Athens (Greece) has a hot-summer mediterranean climate, whereas Porto (Portugal) has a warm-summer mediterranean 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 Athens and to Porto.
Athens is warmer than Porto by 2.7 °C in annual average: 17.5 °C against 14.8 °C.
Porto gets more rain than Athens: 1,278 mm per year against 364 mm.
Athens gets 10.4 hours of sunshine per day on average, against 10.0 hours in Porto.
Athens has warmed by +1.6 °C between 1940 and 2025, against +1.3 °C in Porto. Athens is therefore warming faster than Porto. Both trends are statistically significant.
Athens averages 85 hot days (≥ 30 °C) and 3 frost days per year; Porto averages 11 and 1.
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 | Athens | Porto | Difference |
|---|---|---|---|
| Mean daily temperature | 17.5 °C | 14.8 °C | -2.7 °C |
| Average daily high | 22.1 °C | 18.5 °C | -3.6 °C |
| Average daily low | 13.2 °C | 11.5 °C | -1.7 °C |
| Annual rainfall | 364 mm | 1,278 mm | +914 mm |
| Sunshine / day | 10.4 h | 10.0 h | -0.4 h |
| Hot days (≥ 30 °C) | 85 d/yr | 11 d/yr | -74 d/yr |
| Frost days (< 0 °C) | 3 d/yr | 1 d/yr | negligible |
| Rainy days (≥ 1 mm) | 59 d/yr | 120 d/yr | +61 d/yr |
| Mean relative humidity | 64 % | 79 % | +15 % |
| Average peak wind | 15.4 km/h | 17.4 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.