Data and methodology
How the numbers on this site are produced, what they mean and where their limits are.
- Forecasts
- Forecasts come from the Open-Meteo Forecast API, which picks the best available numerical weather models for each location (national services such as ECMWF, Météo-France, DWD and NOAA). The site downloads them several times a day, and each forecast page refreshes the forecast in your browser when it is more than an hour old.
- Estimated, not observed
- Every value is a model forecast for a grid cell, not a reading from a weather station. The forecast page shows the grid cell used and its distance from the city centre. Differences are largest for coastal and mountainous places, for extreme values and for rain.
- Climate averages
- The climate section of each city page shows monthly averages over 30 years (1996–2025) from the NASA POWER project (MERRA-2 reanalysis, about 50 km grid). Temperatures are adjusted from the elevation of the grid cell to that of the city (−6.5 °C per 1,000 m). Rainfall in reanalysis is smoother than at a weather station: totals for very wet or very dry places can be underestimated or overestimated.
- Reliability
- The first two or three days are the most reliable. Days more than about a week ahead are much less reliable: read them as a trend, not a day-by-day prediction.
- Units
- Values are in metric units: °C, mm, km/h and hPa.
- Licence
- Forecast data: CC BY 4.0, Open-Meteo.com. Climate data: NASA Langley Research Center POWER project, public domain.