'forecaster' originates from English, specifically the base 'forecast' plus the agentive suffix '-er', where 'fore-' meant 'before' and 'cast' meant 'to throw' or 'to cast'.

'forecast' changed from Middle English forms such as 'forcasten' (influenced by Old Norse 'kasta' meaning 'to throw') and later developed into the modern English verb 'forecast'; the noun/agent 'forecaster' was formed by adding '-er'.

Initially, components suggested 'to cast before' (a literal sense of throwing or placing ahead), but over time the compound 'forecast' evolved to mean 'to predict', and 'forecaster' came to mean 'one who predicts'.