Beside the normal Minecraft Weather you also can find special weather in this server. To find details on the normal weather take a look here:

Custom Weather available:

  1. Acid Rain: Looks like normal rain, but actually hurts the player as long as he doesn't take cover. Currently this is easily done by standing under a single block. The chance on Acid Rain is currently 25% on every rainfall. Damage should be a half heart (0.5 hearts or 1 of 20 HPs) each second standing in the open.
  2. Lightning:Lightning only appears when raining. It takes damage and leaves fire when hit. there is more change to get hit when you wear iron armour/sword/tools