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.
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
Data: CC BY 4.0, Open-Meteo.com.