Porto or Rio de Janeiro: which climate?
Porto (Portugal) has a warm-summer mediterranean climate, whereas Rio de Janeiro (Brazil) has a tropical monsoon 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 Rio de Janeiro.
Rio de Janeiro is warmer than Porto by 8.6 °C in annual average: 23.4 °C against 14.8 °C.
Porto and Rio de Janeiro receive comparable annual rainfall, on the order of 1,278 mm.
Porto gets 10.0 hours of sunshine per day on average, against 9.6 hours in Rio de Janeiro.
Porto and Rio de Janeiro are warming at the same rate: about +1.3 °C between 1940 and 2025 on both sides.
Porto averages 11 hot days (≥ 30 °C) and 1 frost days per year; Rio de Janeiro averages 57 and 0.
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 | Rio de Janeiro | Difference |
|---|---|---|---|
| Mean daily temperature | 14.8 °C | 23.4 °C | +8.6 °C |
| Average daily high | 18.5 °C | 26.5 °C | +8.0 °C |
| Average daily low | 11.5 °C | 20.9 °C | +9.4 °C |
| Annual rainfall | 1,278 mm | 1,270 mm | negligible |
| Sunshine / day | 10.0 h | 9.6 h | -0.4 h |
| Hot days (≥ 30 °C) | 11 d/yr | 57 d/yr | +46 d/yr |
| Frost days (< 0 °C) | 1 d/yr | 0 d/yr | negligible |
| Rainy days (≥ 1 mm) | 120 d/yr | 157 d/yr | +37 d/yr |
| Mean relative humidity | 79 % | 81 % | negligible |
| Average peak wind | 17.4 km/h | 16.9 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.