ClearSkies forces the weather to remain clear. I've made this because rain tends to lag my server a little, and it's annoying anyway. Basically this will prevent natural or user weather changes unless they are to a clear weather state, meaning the weather should only ever be clear. The use of /weather rain or /weather thunder will be ignored. IF you encounter rain, it will be from before this plugin was put into use and using /weather clear will change the weather to clear in that area and it will then remain that way until the plugin is disabled.
If you've found a bug or have a suggestion please submit a ticket with all of the relevant information. Bugs or suggestions shouldn't generally be posted in the main page comments.