Children and teens will have a higher chance of being bored when raining. Gloomy sims have a higher chance of being sad from rain and clouds, and are less likely of being happy from sun. The moods are random, it's not like they will always be mathematically sad when it rains, but it can happen. They can be happy or energized when sunny. They can be angry or happy when it snows (not only when they see the first snow), children will be energized anticipating snow fun Sims can be sad, happy or bored when it's raining With this mod, there will be the chance of weather having a bigger impact on your sims mood: I guess adding a more detailed system would have been logic, and that's against Maxis policy. I mean, it does but, very little, and only in some cases.

In The Sims, everything affects mood, even taking a poop, but weather. Nothing can affect a person mood like weather, and if you live in a place where the weather is shit 364 days / year, you know how much rain and cloudy weather can put you in a bad mood.

Sims 4 weather mods