In the Seasons expansion pack, the endless summer is finally broken and your Sims are given the chance to experience Spring, Autumn and Winter as well. Each season has new things for your Sims to experience, including snowman building in Winter and leaf raking in Autumn. Read more here.
Your Sims can now experience all-new types of weather. This includes rain, thunderstorms, hail and more. Read more here.
 Weather Reports
Reading the newspaper and watching the new "Weather Channel" are both ways for your Sims to stay on top of the current and upcoming conditions. The predictions may not be 100% accurate but they're as close as you can get.
 Weather Control Device
The Weather Control Device is a new Aspiration reward for your Sims. Like you may have guessed, it allows your Sim to control and change the weather to be what they please. Make sure their current Aspiration level is Gold or higher, or the device could backfire!
 Leaf Piles
The trees in your Sims' yards now drop leaves! Make sure you rake up the piles, as they lower the room score.
 Corresponding Hairstyles
You can now choose the hairstyles that go with a certain type of outfit. You set them on the third panel in Create-A-Sim.
 New Types of Death
Your Sims can now die in a few different ways! Read more here.
Your Sims can now have gardens where they grow fruit and vegetables. There's also a chance that they could become part of the elusive Garden Club and obtain a special prize. Read more here.
If your Sims happen to have a pond in their yard, they can pull out a fishing rod and cast away. This enjoyable activity is now available to your Sims. Read more here.
 Stackable Inventory
Your Sims' inventories just got a whole lot easier to use! You can now stack up the same items in one spot rather than having a number of the same items lined up.
Do your Sims' children always leave food on their plates? Well, this new feature introduced in Seasons allows your Sims to store uneaten food in the refrigerator for later. The food never goes rotten, so it's a good thing to have for times when there's not enough time to cook.
The Sims 2: Seasons