|Continuing on from Black & White, Pokémon Black 2 & White 2 includes the seasonal cycle
Unlike the day/night cycle however, the seasonal cycle is not completely based upon and dependant on the real world seasonal cycle. Instead, each season lasts a month. This cycle allows for all four seasons to be done within four months, following which, the cycle gets repeated. This means that you will have 3 opportunities to access each season in each year.
The Seasons have several effects upon the game. First, is the obvious aesthetic change. Each season has a slightly different look, depending on what part of Unova you're in. In addition to that, the weather will sometimes change. Normally, it may rain in one area, but it'll snow in that area in the Winter.
In addition to that, the background music will change in a variety of areas to reflect the season. Such as in Winter, you'll hear more bells in most areas and Undella Town's music is more upbeat during Summer. The final effect is the change in the way the time of day works. In previous games, the times that the different parts of the day was static, but here, like in real life, the seasons affect what time each part of the day is.
In addition to this, the Royal Unova leaves each day at varying times.
Encounters & Other Changes
There are some season specific events that run throughout the game.