The Fireworks Display takes place at the end of summer. It's an event you can spend with a special someone.
Attending the Fireworks Display
The Fireworks Display is on Summer 22 each year. You can attend the event in Olive Town any time between 10AM and 9PM that day. When the event is over, you automatically return to your farm at 9PM, so be sure to take care of your livestock and crops before you begin.
Once you enter Olive Town between 10AM and 9PM on the day of the Fireworks Display, time will not pass, so you have plenty of time to talk to everyone and give people gifts for the day before you start the festival. Most people will be in front of the hotel or on the beach. If you can't find someone, be sure to check the map.
How to Participate
To start the Fireworks Display, if you want to do the event alone, talk to Nigel on the beach. Otherwise, you can choose to participate in the event with someone you have given a confession pendant to, or with your spouse. Talk to your desired partner to do the event with them. Saying no will not reduce your relationship with them, and you can talk to them again to do the event with them.
There are no mini-games or challenges in the Fireworks Display, so just watch the events unfold. You will automatically return to your farm at 9PM afterward. You won't be able to go back into town until the next day.