Why look up historical weather
Historical meteorology answers questions with many practical uses. People organising weddings, christenings or outdoor events want to remember -or justify- exactly how the sky looked that day. Insurance companies rely on climatic records to validate hail, flood or late frost claims. Farmers and wineries need to compare seasons: a dry May 2018 versus May 2003 can fully explain harvest differences. Journalists, teachers and history enthusiasts research the weather on D-Day, during the Great Smog of London, the day of a famous Olympics or the year a family member was born.
This tool reads data from the ERA5 reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF), distributed through Open-Meteo. ERA5 blends surface observations, radiosondes, satellites and buoys with a numerical model to reconstruct the global atmospheric state from 1940 to today at ~31 km resolution (~9 km in the ERA5-Land land-only product). Daily outputs include maximum, minimum and mean temperature, liquid precipitation, snowfall and maximum wind.
Limitations: data before 1979 has greater uncertainty due to sparser observations. Precipitation in mountainous areas and convective events may be under-represented. This is not an official station record but a gridded reconstruction, ideal for trends and comparisons rather than for legal evidence (which would require Met Office, NOAA or similar). Even so, the global consistency and the multi-decade coverage make ERA5 the worldwide reference for climatologists.
Common WhatAWeather use cases:
- Weddings and events: "what was the weather on my wedding day in 2017".
- Insurance and forensics: verifying rain or hail on a specific date.
- Agriculture: comparing spring and summer between seasons.
- Journalism: contextualising a historical event with weather data.
- Curiosity: the weather on the day you were born.
Average weather by city and month
Climatology pages with average values, records and rainfall amounts for the world's main cities.