Frost days, hot days and warming trend per city since 1951
Yearly climate indicators of 345 cities, 1951-2025: temperature and anomaly against 1991-2020, rainfall, heavy rain, frost, ice, summer and hot days, tropical nights, degree days and the warmest-year rank; plus warming trends per decade per city.
- Period
- 1951-2025, yearly
- Coverage
- 345 cities in the United Kingdom, Germany, France, Portugal, Serbia and Luxembourg (GB, DE, FR, PT, LU, RS)
- Version
- 1.1.0
- Licence
- CC BY 4.0
- DOI
- 10.5281/zenodo.24187731
Downloads
GB
gb_city_annual_climate_indicators_1951_2025.csvgb_cities.csv
DE
de_city_annual_climate_indicators_1951_2025.csvde_cities.csv
FR
fr_city_annual_climate_indicators_1951_2025.csvfr_cities.csv
PT
pt_city_annual_climate_indicators_1951_2025.csvpt_cities.csv
LU
lu_city_annual_climate_indicators_1951_2025.csvlu_cities.csv
RS
rs_city_annual_climate_indicators_1951_2025.csvrs_cities.csv
Source code and scripts on GitHubZenododata.gouv.frdata.public.ludata.gov.rs
Columns
| Column | Unit | Description |
|---|---|---|
| country | ISO 3166-1 alpha-2 country code | |
| city_id | GeoNames id of the city | |
| name | City name | |
| year | Year (full years only) | |
| tmean_c | °C | Mean temperature of the year |
| tmean_anomaly_c | °C | Difference from the 1991-2020 mean |
| precip_mm | mm | Total precipitation of the year |
| precip_anomaly_pct | % | Difference from the 1991-2020 mean |
| wet_days | days | Days with at least 1 mm |
| heavy_rain_days | days | Days with at least 20 mm |
| max_1day_precip_mm | mm | Wettest day of the year |
| frost_days | days | Days with a minimum below 0 °C |
| ice_days | days | Days with a maximum below 0 °C |
| summer_days | days | Days with a maximum of 25 °C or more |
| hot_days | days | Days with a maximum of 30 °C or more |
| tropical_nights | days | Days with a minimum of 20 °C or more |
| tmax_abs_c | °C | Highest temperature of the year |
| tmin_abs_c | °C | Lowest temperature of the year |
| hdd_15_5 | °C·day | Heating degree days, base 15.5 °C |
| hdd_18 | °C·day | Heating degree days, base 18 °C |
| cdd_18 | °C·day | Cooling degree days, base 18 °C |
| cdd_22 | °C·day | Cooling degree days, base 22 °C |
| rank_warmest | Rank of the year from the warmest (1) | |
| trend_c_per_decade_1951_2025 | °C/decade | Linear warming trend 1951-2025 (in <cc>_cities.csv) |
| trend_c_per_decade_1981_2025 | °C/decade | Linear warming trend 1981-2025 (in <cc>_cities.csv) |
Method
Copernicus ERA5-Land reanalysis grid values (hourly, 0.1°, about 9 km) at the grid cell nearest each city, not station observations. Cities are the 100 most populous municipalities of France and Germany by official population (INSEE, BKG), with their official names, and the largest places of GeoNames cities5000 in the other countries: United Kingdom 100, Portugal 20, Serbia 20, Luxembourg 5. Hourly values are summed or averaged over local civil days in the city’s own time zone, complete days only. Temperatures are adjusted from the grid cell elevation to the city elevation at 6.5 °C per km. Wind is the mean of hourly 10 m wind, not gusts.
Limits
These are reanalysis grid values, not measurements of weather stations: they can differ from official station records, above all in mountains, on coasts and in large cities (the urban heat island is not resolved). They are not official statistics. Daily extremes are smoothed: on record heat days the daily maximum is often 2 to 7 °C below the station record (London, 19 July 2022: 36.4 °C here, 40.2 °C at Coningsby).
How to cite
Weatheo (2026). Frost days, hot days and warming trend per city since 1951 (Version 1.1.0) [Data set]. https://doi.org/10.5281/zenodo.24187731
Licence
Creative Commons Attribution 4.0 (CC BY 4.0). Weatheo (weatheo.com). Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains. German city names and populations: © GeoBasis-DE / BKG (2026), dl-de/by-2-0, data changed.
Changelog
- 1.1.0 (2026-11-13): First release of the city tables (six countries).