In many parts of the world snow falls in the wintertime. Where I grew up, there was usually snow falling around Christmas time.
Snowfall is the second story about Mary and Marcus and their weather machine. In this story, Mary and Marcus learn about snow, while in the earlier story, Rain Machine they learned about rain.
Do you like rain or snow better? Write a story about Christmas or another holiday. You decide what the weather is going to be. It could be hot or cold, rainy or snowy, or a bit of everything all mixed together. Will the weather make it easier or harder to have the kind of holiday your main character wants?