Configure Minecraft weather
After dropping the mod in the mods folder, start the server/client and you can edit the config file to change the MC weather patterns.
On the client you can use the ingame Mod Config editor (via main menu -> mods -> 'WeatherConfig' -> Config OR via pause menu -> Mod options... -> 'WeatherConfig' -> Config).
No comparability with other weather mods guaranteed.
The Math
The config contains 4 pairs of numbers, 2 for rain and 2 for thunder.
The two pairs per weather effect are to set the length of the weather and the time in between.
Every pair has a constant '...Cnt' and a random '...Rnd' part. The constant is always added, the Rnd number is the maximal value for the random part.
The final count (in game ticks) is calculated like so:
time = random(RND) + CNT
This is all explained in the config..