When Does "Ferris Bueller's Day Off" (1986) Take Place?
"Ferris Bueller's Day Off" is a comedy film written by John Hughes that released June 11th, 1986. So when is "Ferris Bueller's Day Off" set?
It takes place in the year:
We know this because central to the plot is a 1961 Ferrari 250 GT California Spyder automobile so it must be during or after 1961 AD.

1985 AD
We know this because central to the plot is a 1961 Ferrari 250 GT California Spyder automobile so it must be during or after 1961 AD.
More specifically, Ferris Bueller and friends attend a Chicago Cubs and Atlanta Braves baseball game. The only game that exactly fits the announcer's descriptions is the one played between these two teams on June 5th, 1985 AD. So the infamous and hilarious "Day Off" must be in June of 1985 AD.
This Baseball Prospectus article examines its exact setting (and this follow up article clarifies that the story takes place on a particular game day that is not the September game day that the scene's shooting happened on in the real world).

