No, Graphcast is a graph transformer trained on ERA5 weather reconstructions of the atmosphere, not a general time series prediction model. It by the way outperforms all traditional global point forecasts (non-ensembles), at least on predicting large-scale global patterns (Z500 and such, on the lag of 3–10 days or so). ECMWF has AIFS that is a derivate of Graphcast, they'll probably get it or something similar to production in a couple of years.