New York
US · 1940s decade mean 11.48 °C → 2010s decade mean 12.09 °C (+0.61 °C across the period).
Linear trend: +0.14 °C per decade
London
GB · 1940s decade mean 10.31 °C → 2010s decade mean 10.81 °C (+0.50 °C across the period).
Linear trend: +0.16 °C per decade
Berlin
DE · 1940s decade mean 8.57 °C → 2010s decade mean 10.26 °C (+1.69 °C across the period).
Linear trend: +0.28 °C per decade
Sydney
AU · 1940s decade mean 16.34 °C → 2010s decade mean 17.61 °C (+1.27 °C across the period).
Linear trend: +0.13 °C per decade
Cape Town
ZA · 1940s decade mean 16.54 °C → 2010s decade mean 17.09 °C (+0.55 °C across the period).
Linear trend: +0.08 °C per decade
Tokyo
JP · 1940s decade mean 14.08 °C → 2010s decade mean 15.06 °C (+0.98 °C across the period).
Linear trend: +0.18 °C per decade
Notes on method
- Source. ECMWF ERA5 reanalysis, accessed via the Open-Meteo Archive API. Licence: CC BY 4.0.
- Period. 1940-01-01 to 2024-12-31.
- Aggregation. Daily 2 m mean temperature → annual mean (simple average across the year's daily values).
- Trend. Ordinary-least-squares regression of annual mean against year, expressed as °C per decade.
- Refresh. Data is pulled at build time; the date in the site footer is the build date.
- Limits. A single grid-point per city. Reanalysis is not a thermometer reading — it's a model assimilation of observations and is most reliable for trend, less so for absolute values in regions with sparse historical coverage.