London or Porto: which climate?
London (United Kingdom) has a temperate oceanic 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 London and to Porto.
Porto is warmer than London by 4.6 °C in annual average: 14.8 °C against 10.2 °C.
Porto gets more rain than London: 1,278 mm per year against 615 mm.
Porto gets 10.0 hours of sunshine per day on average, against 7.5 hours in London.
London has warmed by +1.8 °C between 1940 and 2025, against +1.3 °C in Porto. London is therefore warming faster than Porto. Both trends are statistically significant.
London averages 1 hot days (≥ 30 °C) and 36 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 | London | Porto | Difference |
|---|---|---|---|
| Mean daily temperature | 10.2 °C | 14.8 °C | +4.6 °C |
| Average daily high | 13.4 °C | 18.5 °C | +5.1 °C |
| Average daily low | 6.9 °C | 11.5 °C | +4.6 °C |
| Annual rainfall | 615 mm | 1,278 mm | +663 mm |
| Sunshine / day | 7.5 h | 10.0 h | +2.5 h |
| Hot days (≥ 30 °C) | 1 d/yr | 11 d/yr | +10 d/yr |
| Frost days (< 0 °C) | 36 d/yr | 1 d/yr | -35 d/yr |
| Rainy days (≥ 1 mm) | 123 d/yr | 120 d/yr | negligible |
| Mean relative humidity | 80 % | 79 % | negligible |
| Average peak wind | 20.4 km/h | 17.4 km/h | -3.0 km/h |
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.