At a minimum, readers know that Fahrenheit 451 takes place sometime after 1990. The story may take place in the later 1900s or well into the 21st century.
some time after 1990 with a sort of futuristic setting
Explanation:
Guy montag in the book says: 'Every hour so many d*mn things in the sky! How in h*ll did those bombers get up there every single second of our lives! Why doesn't someone want to talk about it! We've started and won two atomic wars since 1990!'. We don't know when exactly it took place.
