The world map places are rainy. Could this be another plot, perhaps?

There's an increased chance of Tempest appearing in rainy areas.

Edit: Got that a bit wrong. Not just rainy areas. It's all over the map, and increases the chances of her appearing anywhere.

Ah, I see! :D

Happens for 3 hours on Monday's only. Tempest doesn't like Monday.

I've never happened to visit the map during the right time, and had no idea this even existed! Very cool :)

What happened, if it rain on the map?