How the weather changes

Changes between consecutive days · one ECMWF forecast run
ECMWF · BETWEEN DAYS← Meteorix
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ECMWF forecast run:
Drag · scroll to zoom · select a location to compare values
Each color represents the dominant change relative to its threshold. Millimetres, degrees and gusts are not combined into a danger index.
· ECMWF Open Data · CC BY 4.0
Forecast-day comparison from a single run. Sampled temperature maxima and gusts. Thunderstorms: environment at 18 UTC, not observed lightning or probability.
Preparing consecutive days…
Data included · works offline

How weather changes from day to day

Different days forecast by a single model run are compared, for example Thursday versus Wednesday. Days are UTC worldwide, not local calendar days for individual cities.

Noticeable threshold: 10 mm, 2 °C, 15 km/h or one convective level. Large: 30 mm, 6 °C, 35 km/h or two levels. With “All changes”, the phenomenon exceeding its threshold most is selected; physical units are never added together.

ECMWF data at 0.25° resolution, native-centre sampling at 0.5°. Values rounded to 0.1 mm, 0.1 °C and 0.1 km/h. Selecting the map uses the nearest grid centre.

The server uses the latest 00 UTC run with four complete days available. It checks for updates in the background and keeps the last valid map if a download fails. Dates identify the data displayed.

ECMWF Open Data · CC BY 4.0. Forecast changes, not official warnings.