This day is supposedly the longest day of the year, the sun set will fall later on this day than any other day. If the player talks to Tortimer, they will receive an Expresso Maker. Tortimer can be found outside the Mayor's Office, north in the town.
In new leaf it has changed to the summer solstice. Talk to Isabelle and she will give you some ladder shades. There will also be a photo cutout! It will be sunny all day and night, with no clouds in the sky. You will still be able to catch night time bugs, like tarantulas.