Rome or Tokyo: which climate?
Rome (Italy) has a hot-summer mediterranean climate, whereas Tokyo (Japan) has a humid subtropical 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 Rome and to Tokyo.
Rome and Tokyo have the same mean annual temperature, about 15.2 °C: the gap between the two cities is too small to be told apart from the noise in the data.
Tokyo gets more rain than Rome: 1,376 mm per year against 860 mm.
Rome gets 10.0 hours of sunshine per day on average, against 8.2 hours in Tokyo.
Rome and Tokyo are warming at the same rate: about +2.0 °C between 1940 and 2025 on both sides.
Rome averages 43 hot days (≥ 30 °C) and 17 frost days per year; Tokyo averages 36 and 34.
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 | Rome | Tokyo | Difference |
|---|---|---|---|
| Mean daily temperature | 15.2 °C | 15.3 °C | negligible |
| Average daily high | 20.1 °C | 19.1 °C | -1.0 °C |
| Average daily low | 10.7 °C | 12.0 °C | +1.3 °C |
| Annual rainfall | 860 mm | 1,376 mm | +516 mm |
| Sunshine / day | 10.0 h | 8.2 h | -1.8 h |
| Hot days (≥ 30 °C) | 43 d/yr | 36 d/yr | -7 d/yr |
| Frost days (< 0 °C) | 17 d/yr | 34 d/yr | +17 d/yr |
| Rainy days (≥ 1 mm) | 107 d/yr | 134 d/yr | +27 d/yr |
| Mean relative humidity | 74 % | 74 % | negligible |
| Average peak wind | 13.8 km/h | 19.9 km/h | +6.1 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.