Rain



Rain is a feature activated by pressing F5 in-game in Classic. Rain can also fall on Multiplayer, but cannot be seen by other players. It will only fall where the sky isn't blocked, and currently has no effect on gameplay. Rain is a single moving sprite. When it falls on a block it makes a splashing effect. To improve frame rate, rain isn't replicated all throughout a map. It is instead one sprite on all sides of the player. When the player goes inside and far away from the falling rain it disappears but reappears when you move close to outside again. Water does not stop rain like a solid block. Instead, it falls through as if there was air. The same applies to lava and small plants. It is currently not in Beta. But rain is planned to be back in a later update. There is a discussion on rain here on the Minecraft Wiki. Rain sprite is still in Beta files.

Rain in Beta
Notch announced that rain, along with falling snow will be added in 1.5 Beta. The rain will water crops, regrow snow and ice, make wolves wet , put out fires (including mobs on fire ), fishing in rain will possibly have higher odds of catching fish and it will possibly fill up small holes with water. During rain, light level will be one level darker and you won't be able to see moon or sun. Rain will be temporal and global, thunders are also confirmed