Past Tense of “forecast”
The past tense of forecast is forecast/forecasted; the past participle is forecast/forecasted.
Why “forecast” behaves this way
"Cast" itself is a relatively late arrival in English, borrowed from Old Norse "kasta" (to throw) around the 13th century, well after the Old English strong-verb system had mostly stopped adding new members. Rather than being assigned to any existing strong-verb ablaut class, it was absorbed into a small unmarked group of monosyllabic verbs — "cut," "hit," "put," "set," "shut" — where the base form, past tense, and participle are all identical. The modern practice of publishing daily weather forecasts dates to the 1860s, pioneered in Britain by Robert FitzRoy, who coined the very term "forecast" in this specialized sense to distinguish scientific prediction from mere prophecy — a 19th-century technical innovation layered onto a verb whose grammar was already many centuries old by that point.
"Forecast" is simply "fore-" (before) plus "cast," a compound that emerged once "cast" had already settled into English with its unmarked conjugation, so the compound never had a chance to develop separately — it inherited the unchanging pattern automatically, the same way "forget" and "forgive" inherited their base verbs' irregular forms rather than developing new ones.
The common confusion
"Forecasted" has become genuinely common in modern business, finance, and meteorology writing ("the model forecasted a 3% increase"), competing with the traditionally correct unmarked "forecast" — this is one of relatively few zero-change verbs currently drifting toward regularization in specialized technical writing rather than staying fixed. A further wrinkle involves "weather forecaster" versus "economic forecaster" as job titles, both built on the noun form of the same word, which never changes regardless of which past-tense verb variant a given industry prefers. Every one of those fields shares the identical grammar underneath, which is exactly how one word ended up comfortably covering rain, revenue, and election results all at once.
How it's actually used
In everyday weather talk, "forecast" stays unmarked almost universally ("they forecast rain"), while in financial and corporate writing, "forecasted" appears often enough that most style guides now treat it as acceptable rather than an error, reflecting the word's split professional usage. Corporate earnings calls and financial media use "forecasted" so consistently that some readers now perceive the traditionally correct unmarked "forecast" as the less natural choice in that specific context, even though meteorologists and most style guides still treat plain "forecast" as standard across both fields.
Across the tense system
The participle behaves the same as the simple past in both variants — "has forecast" or "has forecasted" — so whichever form a writer settles on for the simple past should carry through consistently into the perfect tenses within the same document. Government and scientific agencies overwhelmingly prefer the unmarked "forecast" in official reports ("the agency forecast below-average rainfall"), reserving "forecasted" mostly for less formal business contexts, a genuine register split worth tracking for writers moving between the two worlds. Sports commentary borrows the same verb loosely ("analysts forecast a close final"), extending meteorological vocabulary into an entirely unrelated competitive context without any grammatical adjustment.
Common real mistakes
Beyond the forecast/forecasted split, a further error is treating the noun and verb identically in constructions where only one works — "the forecast called for rain" (noun) is fine, but "they forecasted a forecast" is redundant, an awkward doubling that shows up when writers aren't tracking which word is functioning as which part of speech in a longer sentence.
Examples
- Meteorologists forecast heavy rain for the weekend.
- The company forecast a strong quarter despite the slowdown.
- Analysts had forecast a much smaller drop in sales.
- She forecasted the trend two years before it happened.
- The report has forecast steady growth through next year.
- They forecast the storm's path with unusual accuracy.
- Economists forecasted a mild recession that never fully arrived.
- The budget was forecast based on last year's numbers.
- The agency forecast below-average rainfall for the entire season.
- Investors reacted before the earnings were even forecast.
Memory trick
Remember "cast" doesn't change, so neither does its compound: cast a spell, cast a vote, forecast the weather — all identical in every tense, exactly like "cut" and "set," its unmarked-verb relatives.