How to make a Snowing sky
No scripting needed!
To start off, open the Home tab, then click on Part and add in a Block to start off with. If you failed this step then don’t worry because there is more to come and it’s only going to get harder!
You should see something like this:
Once you’ve inserted your part, move it up in the sky and scale it to the size of your map. If you want to you can make the part invisible by changing its Transparency to 1 but for this tutorial its going to be visible.
Make sure the part’s Anchored = true and CanCollide = false in the Properties tab.
This is what it should look like:
Next your going to open the View tab and open Explorer. Then your going to want to hover over the part you inserted, click the plus and insert a ParticleEmitter into it:
Click plus: 
Add ParticleEmitter: 
Now you should see particles floating out of the part:
Lets go! The particles are floating upwards! BUT not for long they aren’t!
To remove this issue, click on the ParticleEmitter inside of the part then scroll down until you see EmissionDirection. Set the value of this to Bottom.
Sweet! Now the particles are flowing the right way:
For the final part of this tutorial, we are going to change the sparkle image to snow!
Go to the Home tab and click on Toolbox. Next go to images and type in circle (which is going to be the snow image)
Scroll down until you find this image which is barely visible:
Left click on the image and press Copy Asset ID. Then click back on the ParticleEmitter and find Texture:
Remove the text inside the box and paste the Asset ID you copied into it. Congratulations! you just made snow! You can adjust the ParticleEmitter settings to whatever suits you and your game!
Invisible part:
Visible part:
Hope this helped 
- @AustnBlox