weather command
Weather command is used to change/clear weather
clear will clear the sky and turn blue. It will stop raining/snowing.
rain will darken the sky. It will start to rain (in a snow biome, the rain will appear as snow).
thunder will darken the sky. It will start to rain and then thunder/lightning.
duration is optional. It is the length of time (in seconds) that the weather cycle will last.
How to use weather command
Type /weather {weather} {duration}
EXAMPLES
/weather clear
/weather rain 9214
/weather thunder