The Sims 3: Seasons is an expansion to the real-time life management simulator Sims 3. The update adds seasons and a ton of new content to the game. Along with the addition, you will notice how the game environment changes when the season changes or it rains. The weather affects Sims just as much as the environment. So, for example, your Sim may develop an allergy in the spring and will have to treat it.
The add-on requires the original version of The Sims 3.