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ECMWF data can be differentiated into 3 main categories: analyses, "instantaneous" forecasts and accumulated forecasts.

• Analyses are produced by combining short-range forecast data with observations to produce the best fit to both. The data are available a few times per day.
• "Instantaneous" forecast data are produced by the forecast model, starting from an analysis, and are available at various forecast steps (hours) from the analysis date/time. These data are relevant to a particular validity date/time (forecast start date/time plus step), see the article on Parameters valid at the specified time.
• Accumulated forecast parameters are accumulated over particular periods. In some datasets the period will be from the beginning of the forecast (eg in ERA-Interim), while in ERA5 the period is since the previous post processing (archiving). You can divide values by the length of the accumulation period to calculate averages over the accumulation period.
• Minimum or maximum forecast parameters are the minimum or maximum during a particular period.

Some parameters are only analysed, some are only forecast (e.g. radiative fluxes) and some are both analysed and forecast (e.g. temperature, winds and pressure).

No, the ECMWF weather forecasts are not available through Copernicus. Essentially ECMWF's activities to implement the CAMS and C3S Copernicus services are separate from ECMWF's mandate to produce weather forecasts.

Some ECMWF products are publicly available for free. Others, in particular the 10 and 15 day forecasts, are only available to specific user groups or for a fee. For further information see here.

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