Board Thread:The Heroes of Olympus/@comment-29729973-20161016134842/@comment-29068459-20170914024652

Well, lemme kind of clear up what I was saying. You are right in saying that Percy is always stronger when around water than when not around it. After all, the creek at Camp Half Blood is fresh water. However, Percy is at his most powerful when in sea water.

Remember how the Nereid who talked to Percy in The Lightning Thief couldn't stay in the Mississippi River for long, because she was an ocean water spirit? Well, Percy is more stable than that, being the son of Poseidon, and he has a lot of control over fresh water. But Poseidon is the god of sea storms, so when Percy creates a storm, it must come from the sea.

However, you are right in saying he probably could use moisture in the clouds for stuff, since he was capable of utilizing petrified sea shells for massive water output. But I just don't think he could pull off a hurricane.