There are probably lots of players out there who are wondering about the specs for Seasons, and how the game will impact their PC. SimGuruGraham commented on the Specs for Seasons with the following:
We aren’t raising the min spec for Seasons. The detail of the weather effects scales across different hardware so that everyone can enjoy the experience.
The weather effects will vary from computer to computer, but keep in mind that with every expansion and stuff pack installed, the specs raise. The minimum specs for any single game, are only for that specific game + the base game. The bare minimum. For reference, the specs for Seasons can be found here.