I claim "near-future" to be one word and not too late. I would also change "will be" to "is" to make it even less unplanned.
There is a near-future event at the town hall.
You can even try "soon-to-be" even though it isn't really used that way. Maybe invent "soon-to-be-recent"?
https://en.wiktionary.org/wiki/soon-to-be
There is a soonish event at the town hall.
"Soon" is a good word for the near-future, but it would require slight rewrite.
"Soonish" is a casual word that should work well as adjective even if it may be seen as as an adverb only.
https://en.wiktionary.org/wiki/soonish
When you say future is too vague, maybe the actual date can serve your purpose.
There is a Saturday event at the town hall.
I would also recommend "planned" if a date was too specific.
If the event isn't really planned, maybe "pending / impending" is your go.
https://en.wiktionary.org/wiki/pending
Plenty of possibilities, depending of what the actual use and style is. I would second the vote for "upcoming" as rather similar to "recent" . It works as a header for a list of events as well as for heads-up in a news-letter or on a poster.
Remember the upcoming/recent event at the town hall!