How weather forecasts work

Modern forecasts come from numerical weather models — physics simulations of the atmosphere running on supercomputers. They start from a snapshot of the current state (temperature, pressure, wind, humidity at thousands of points around the globe) and step the equations forward.

Where the data comes from

Three of the most cited models worldwide are ECMWF (Europe), GFS (NOAA, USA) and ICON (DWD, Germany). Open-Meteo blends them and exposes the result through a free API; that's the data we serve on every page here.

How far ahead is usable?

Accuracy is highest in the next 24 hours, very good up to 5 days, softer beyond. The 14-day view is a tendency, not a promise — useful to spot a heat wave or storm window forming, less so to plan a precise outdoor event two weeks out.

How often we refresh

Our database is updated every two hours by a background job. Cloudflare keeps cached pages warm in between, so a city page typically renders in milliseconds.