Storm Kings Flood

When the ever hibernating Storm Kings and Queen decide to take flight every few years, the surrounding areas are blanketed in some of the heaviest rain in the world. The rain gets so heavy that great floods occur, albeit not for long. The people of the surrounding areas have built and reinforced their villages and cities in preperation for whenever a Storm King flies, although the downpour gets infinitely worse when the Storm Queen takes flight.

Manifestation

The floods start out as a lasting light drizzle of rain, people that live in the areas most affected by these floods can recognize between when it is just rain and when a Storm King is flying. The rains progressively get harsher as the Storm King makes its way towards the land up until the Storm King is above the land itself, providing a torrential downpour on the people below.
The floods themselves are not the only part, as when the waters wash away the lands especially touched by the downpour can form unique wood and metals, known aptly as Stormwood and Stormstone, being able to imbue gear made out of it with the minor power of a Storm King, due to the origin of Storm Kings being traced back to Elementals.

Localization

Storm Kings do not fly far from the Isles Of Storms, as the land is named that due to forming above their nest. The areas most affected by these floods are the coasts of Osteodor, Sciadan, The Old-Growth Isles, and some of the Willowdale Isles. These areas have been nicknamed stormy coasts by the locals who live outside these affected areas. For the cities and villages within the affected areas however, live moves on as normal, as they've grown accustomed to the floods that sometimes ravage the lands, simply staying inside and building their cities in such a specific way that they can withstand even the Storm King flying right above.
There are times however when a Storm King may fly further outside its path, though these occurences are rare they have happened in the past, leading to some disaster as those further from the Isles of Storms are not as prepared for one to take flight.