WinterWibe:

With the help of his plugin you can make snow fall all over the server without the need for a snow biome

Commands:

/ww true - "enable snow"
/ww false - "disable snow"
/ww ficks true/false = version 1.0 . Changed biomes from Netherworld to Overworld biomes, If you Enable (True) this command then the plugin will automatically Fix biomes back to Netherworld (The plugin will Fix all biomes that will be loaded until you write 
/ww ficks false)
/ww timer true = enable automatically turn on snow on a timer that you set in the config.
/ww delsnow true\false = The winter is to end and i think much peoples do not want to have snow all time, so this command delete all snow that is not at snow biomes, Please Make world Backup Before start this command, because she can make mistakes and delete snow that actually shold stay there.

NEW Version 1.8:

Commands New:

/ww anotherbiomdetool = Then you get a stick, you can set a territory, like in the "Privat Plugin" Then you can write a next command.
/ww anotherbiome [biome] = set biome at terrytorry that you set. example command /ww anotherbiome Plains

Config:

# Speed of snow accumulation (1.0 = normal Minecraft speed)
# Higher value = snow covers ground faster.
snow-speed: 1.0

# Settings for the Nether Biome Fixer (/ww ficks)
nether-fix:
  # Should the plugin print a report to the console every 10 minutes?
  log-to-console: true

# Automatic Winter Timer Settings
timer:
  # How long will the pause (in minutes).
  # 60 means how long after 1 snow the plugin will wait to start 2.
  interval-minutes: 60
  
  # How long the winter lasts (in minutes).
  # Example: 10 means it snows for 10 minutes, then stops.
  duration-minutes: 10

Recommendations:

If you have snow enabled, it is advisable to disable it before restarting or shutting down the server. Nothing will happen if you forget, but it is better to be sure that nothing will happen.

Minimal Speed: 0.34

Another info:

A little story about why I created this plugin:

I wanted to add a little Christmas cheer to my server and decided to make snow all over the server, but when I searched almost everything I could, I couldn't find what I wanted, so I created a plugin :).

Approximate operation of the plugin:

When you write /ww true the plugin saves data about the chunks that are loaded and then changes all the chunks that are loaded to chunks of the snow biome.
And when you write /ww false, then all the chunks that the plugin changed, the plugin puts on the biome that was there before