When you look at a graph for a term over time, you’ll see the option to check the Forecast box. This forecast shows how popular the term is expected to be in the near future. These forecasts are only estimates, not exact predictions of future values.
How forecasts are determined
To predict the popularity of a term in the future, Trends looks at how many people searched for that term in the past. Trends doesn’t take into account the context of the search term or its category.
Why certain terms don’t have forecasts
Trends doesn’t show forecasts for terms that are particularly difficult to predict. Also, if a short time range is chosen for the term, it can be difficult for Trends to generate enough data or history for the term you entered.