/ˈfɔːrkæst/
[verb] To say what you think will happen in the future, based on information or evidence you have now. It can also be used as a noun to describe the prediction itself, such as a weather forecast.
Before meteorologists existed, 'forecast' meant planning ahead in battle — soldiers forecast, not scientists.
The word 'forecast' is built from two pieces that were both already alive in Old English and early Middle English: the prefix 'fore-', meaning 'before' or 'in advance', and the verb 'cast', which in medieval English carried the powerful sense of 'to throw', 'to plan', or 'to calculate'. Together, they created something remarkably practical — to throw your mind forward in time, to reckon what lies ahead.
The verb 'cast' itself travelled a long road before it settled into English. It arrived from Old Norse 'kasta', meaning 'to throw', which Norse-speaking settlers and raiders brought to Britain during the Viking Age, roughly the 8th to 11th centuries. Old Norse kasta → Middle English casten, where the meaning quickly broadened from physical throwing to mental projection — casting your thoughts, casting accounts, casting a plan. This mental sense was essential to the birth of 'forecast'.
The prefix 'fore-' comes directly from Old English 'fore', meaning 'before' in both time and space, which is itself a cousin of the Latin 'pro-' and Greek 'pro-', all descending from the ancient Proto-Indo-European root '*per-', meaning 'forward' or 'in front of'. English kept its own native version clean and simple, and 'fore-' became one of the most productive prefixes in the language — giving us 'forewarn', 'foresee', 'forefather', and dozens more.
When 'forecast' first appeared in writing in the late 14th century, it meant something very close to 'to plan in advance' or 'to contrive beforehand'. A military commander might forecast a strategy; a merchant might forecast his route. The idea was deliberate, careful thinking ahead — not passive prediction, but active mental preparation. This is subtly different from how we use the word today, and it is worth pausing on: early 'forecast' was about human agency, not about reading nature's signs.
The shift toward predicting natural events — weather in particular — came gradually over the following centuries. As navigation, farming, and trade grew more sophisticated, the need to anticipate weather became urgent and practical. By the 17th and 18th centuries, 'forecast' was being used in almanacs and nautical journals to describe predictions about storms, tides, and seasons. When professional meteorology emerged in the 19th century, the word was perfectly positioned to become its central term. The Meteorological Office in Britain, founded in 1854, helped cement 'weather forecast' as an everyday phrase that almost every English speaker now uses without a second thought.
What is quietly remarkable about 'forecast' is how neatly it preserves an ancient metaphor: the idea that thinking about the future is a physical act, a kind of throwing. When you cast a fishing line, you send it out into uncertain water, not knowing exactly where it will land. When you forecast, you do something almost identical with your mind — you send your thinking out into the uncertain water of time ahead, and hope it lands somewhere close to the truth.