In the present study an exploratory analysis of the relationship between regional fAPAR time-series and yield inter-annual variability in the period 1999-2012 has been conducted, evaluating its reliability for operational crop yield forecasting activities. Overall, the results indicated strong correlation between fAPAR and official yields in water-limited yield agro-climatic conditions for all the three crops studied. Where crops are subjected to frequent water stress, e.g. the Mediterranean basin, the Black Sea area, most of the yield inter-annual variability is explained by leaf area formation along the growing season, and can be well captured by regional fAPAR time-series. By contrast, in the regions of high yields, where generally fAPAR inter-annual variability is low as consequence of rainfall regimes close to potential evapotranspiration (or intensive irrigation in the specific case of grain maize) the correspondence between fAPAR and yield anomalies is weak. Yield variations are explained by other factors than leaf area formation (e.g. excess of rain during harvest), and therefore extreme yields in those regions are not necessarily corresponding to large fAPAR anomalies. The use of remote sensing in operational crop yield forecasting at regional scale therefore requires the consideration of additional, independent indicators: weather parameters, crop models, etc. EO biophysical products provide, indeed, a synoptic view of the vegetation status and leaf area formation along the growing season. Nevertheless, the results of this study indicates that their interpretation may be sometimes misleading when used alone to explain extreme yields. ; JRC.H.4-Monitoring Agricultural Resources