Crestfallen is two worlds, not one. The Mortal world—called Kerun, and the spirit world, called the Otherlands. They were once the same place (called An-ki), but were ripped apart by the creator goddess Earth Mother. The barrier between these two worlds is thin in some spots, thick in others. Where it is thin, weather fronts from both sides collide against each other—and cause all kinds of chaos. If that wasn’t bad enough, the god of nature has been murdered, and the god of weather is mortally wounded. The seasons of the Otherlands are now misaligned, when it is summer in the Otherlands, it is winter on Kerun. This is the reason that the weather in Crestfallen is such a big deal, when a supernatural snowstorm from the spirit world clashes with the worst drought in living memory in the mortal world—danger happens!
Weather is just as terrifying and powerful as any monster, it can snuff out a city as easily as a lone traveller.
The weather rules in Crestfallen interact with every other chapter of the game. The players decide the current weather calamity during character creation, and include it in the story. Weather attacks the group when they are travelling in the wilderness, only good planning and survival skills can save them. Weather can also attack ships, cities and armies with equal force. It ignores the size of it’s target, as it is on an entirely different scale. Ritualists can alter the weather through magical rituals; ending droughts, averting volcanoes and so on. Ritualists are highly cherished by their communities!
Natural disaster also enhances the story of Crestfallen sessions. Players might botch an important magic ritual, and cause an earthquake that levels a nearby town. A flood might devastate an important city, and the PCs must help in the rescue operation to gain the trust of the city leadership. A sentient cyclone of air spirits in the Otherlands could be a powerful ally if only you knew it’s agenda.