[quote=Feisty-Pants]
.....

=_=

So you're saying you're useless in dry environments. Just like how someone who manipulates fire is useless in the rain.
[/quote]

Why would the rain stop a fire though xD The heat will evaporate the drop before it does anything to it. Think of a Pyromancer as being two of the three elements needed to start the Fire: Fuel and Ignition :P Pyromancers would probably have a hard in places where the air is thin with oxygen.

For the question of Salty. I would have to say you could probably create your own source of water, but would take much more energy than if you already had a source of water to play with. It would be the same for a Pyromancer. If there is no fire or no fuel for fire in the area, it is safe to say they can still use their magic but would require more energy and concentration.