Porto or Vienna: which climate?
Porto (Portugal) has a warm-summer mediterranean climate, whereas Vienna (Austria) has a warm-summer humid continental 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 Porto and to Vienna.
Porto is warmer than Vienna by 4.9 °C in annual average: 14.8 °C against 9.9 °C.
Porto gets more rain than Vienna: 1,278 mm per year against 639 mm.
Porto gets 10.0 hours of sunshine per day on average, against 8.3 hours in Vienna.
Vienna has warmed by +2.4 °C between 1940 and 2025, against +1.3 °C in Porto. Vienna is therefore warming faster than Porto. Both trends are statistically significant.
Porto averages 11 hot days (≥ 30 °C) and 1 frost days per year; Vienna averages 12 and 83.
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 | Porto | Vienna | Difference |
|---|---|---|---|
| Mean daily temperature | 14.8 °C | 9.9 °C | -4.9 °C |
| Average daily high | 18.5 °C | 14.0 °C | -4.5 °C |
| Average daily low | 11.5 °C | 6.1 °C | -5.4 °C |
| Annual rainfall | 1,278 mm | 639 mm | -639 mm |
| Sunshine / day | 10.0 h | 8.3 h | -1.7 h |
| Hot days (≥ 30 °C) | 11 d/yr | 12 d/yr | negligible |
| Frost days (< 0 °C) | 1 d/yr | 83 d/yr | +82 d/yr |
| Rainy days (≥ 1 mm) | 120 d/yr | 118 d/yr | negligible |
| Mean relative humidity | 79 % | 74 % | -5 % |
| Average peak wind | 17.4 km/h | 18.3 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.