Forecast vs. forecasted

  • Both forecast and forecasted are widely used as the past tense and past participle of the verb forecast, but the uninflected form is more common. In 21st-century English it prevails by a large margin, but not by such a large margin that anyone should consider forecasted wrong. The ratio of the past-tense and participial forecast to forecasted in 21st-century newswriting is about 20 to one, and it’s five to one in books (where forecasted is disproportionately common in financial writing) and two to one in scientific and scholarly writing.


    The second syllable of forecast derives from the earlier verb cast, which has usually gone uninflected throughout its eight centuries in English. But forecasted has always been more common than casted (relative to forecast and cast, respectively) and is accepted to a degree that casted has never attained outside specialized uses. Treating forecast the same as cast might seem logical, but English usage isn’t guided by logic.



    Both forms are easily found in diverse types of writing. Here are a few examples:

    Clearly, we would be happiest if the two forcasting methods have forecast errors with large negative correlation. [Introduction to Time Series Analysis and Forecasting]

    Many forecasted that Mitt Romney would defeat President Obama in the 2012 presidential election. [Guardian]

    [T]he forecasted demand for bioartificial organs—cellular, autograft, allograft, and xenograft transplants—is estimated to be in the billions of dollars per annum. [Nature]

    The company’s analysts had forecast it would take as long as nine months to find that many qualified engineers in the United States. [New York Times]

    To demonstrate his orthodoxy and his attachment to the Church and its triumph he composed works in which he forecasted its universal greatness. [History of Italian Philosophy, Eugenio Garin]

    But at the same time, other studies have forecast that warmer temperatures will reduce the wind shear necessary to turn a routine thunderstorm into a powerful system that can give birth to tornadoes. [Time]


    1. “writers writers”

    2. WorldWideWEB says

      Thank you for this info.

    3. Keith McClary says

      In the first example, “forecast error” is a technical term referring to the amount of error in a forecast.

      • Keith McClary says

        “if the two forcasting methods have forecast errors”

        What I am saying is that “have” means “possess” here. This is clear from the cited context.

        The Grammarist is incorrectly reading “have forecast” as the past tense of a verb.

        Take any advice from the Grammarist with a ton of salt.

        • Keith McClary says

          Let me try once more to explain.

          This usage of “forecast error” is similar to “Lengths are subject to measurement error of one millimetre”.

          “Forecast” is a noun in the example.

          • Your correction is accurate. Your conclusion that one error requires application of “a ton of salt” is … hyperbolic.

    4. Further to Keith’s note. “Forecasted” will stand alone as a past-tense verb whereas “forecast” normally requires a helper. For example either of these sounds fine:
      1) “Last month I forecasted snow”
      2) “Last month I had forecast snow”
      …but the following will sound wrong:
      3) “Last month I forecast snow”.

      • Actually, (3) sounds fine to me. It might be a regional difference.

        Keith stresses that “forecast” in “forecast error” is a noun, (or adjective) -the kind of error it is, is a forecast one: an error associated with the process of forecasting, it is not the case that the errors have been forecast(ed).

        However, in (3) “forecast” is still a verb, and, like (3), I am quite happy to talk about “the snow I forecast” (in the same sense as “the snow I foretold”).

        • Keith McClary says

          By “forecast error” the meteorologists mean the inaccuracy of their forecasts (eg. +/- 1 degree). They are not trying to forecast their errors.

      • Guy Nonplussed says

        Just as a data point, I agree with Rosie regarding (3). It sounds fine to me. In fact I had never been conscious of “forecasted” at all until relatively recently, since doing a lot more financial reading. It sounds wrong to my ears which is what brought me to this page. Evidently it is widely used in some circles, and logically I appreciate that it is less ambiguous and more regular. I don’t expect to change my own usage, but I’ll stop cringing when I see it.

        • Isn’t “forecast” also its own past participle? People who say “forecasted” sound like 7 year olds to me.

          • According to the article we’re reading: Can be, doesn’t have to be, and in some areas of knowledge the -ed form is comparatively more common.

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