Don't worry, take your time. If you need an extension I might be able to give you one valid on the reasoning.
Well, what is Rayquaza known for in the game lore?
It is unaffected by the weather conditions, is able to calm Groudon or Kyogre with ease, so perhaps it can cancel out weather affects or "calm" the weather conditions.
Rayquaza is also known for always being up high into the ozone, and rarely comes to to ground unless resting briefly upon the sky tower. It is very territorial, and considered one of the most powerful pokemon in existence.