What disadvantages are there from being wet?

Recognized by dripping clothes. Attempting to conjure a lightning element whilst in this state will damage a wizard and cause him to lose charges. Thus, it is impossible to cast any spell involving a lightning element while wet.

Wet characters also take twice as much damage from lightning spells. Being Wet will remove Grease/Burning.

Source: Magickapedia

• If you do a lightning spell while wet, you'll be damaged.
• In co-op mode, you cannot resurrect your partner if you are wet since it requires lightning.
• You'll freeze if you get hit by a cold spell.

Aside from the effects listed above, you'll also note that anytime your character (or an enemy) takes cold damage while being wet, they will be frozen solid and unable to move or take action. Some enemies are freeze-proof, however, some spoiler related bosses in particular.