From JC2-MP Documentation
Weather severity values go from 0 to 2. 0 is clear weather with no low-altitude clouds. 2 is the maximum weather possible.
It is region-dependent; it will never snow in desert areas.
Panau's weather is stubborn and will often not do what you tell it to. You can set the weather severity to 2 and it may refuse to rain for a few minutes, even in a rain forest. Then suddenly it will start pouring. Sometimes it starts raining with a value of 0.5.
Use '/weather 1.2345' to change the weather for the default world
local words = args.text:split(" ")
if #words ~= 2 then
local value = tonumber(words)
if words == "/weather" and value then
Chat:Broadcast("Setting weather to "..value, Color(255, 255, 255))