Magical weather is something I rarely see in setting write ups. There is at least one dedicated file for the idea, Caelumancy by Bards and Sages, but that is for PCs treating weather as magic items (i.e. feats and rules for making magical weather). So here are some ideas on weird, magical weather I would consider for fantasy settings like Oathbound and Midnight.
Though most clouds and rain are made of liquids (or fluids), there are some that drop solid materials. Soil, moondust, ash and corpsedust are all possible. Soil is from another place on the planet, the result of dust storms and extreme erosion. Lands that get a lot of it have to keep up in cleaning off their infrastructure or be willing to live underground. Moondust is actual material from one or more moons. It alters the color of the sky, thus affecting what plants can and can not grow. Ash can be considered reverse water as it causes the land to dry out. Corpsedust is bits of dead gods. When it falls, the effects relate to the god(s)' divine powers.
Living things can fall from the sky. Seeds, spores, eggs, plants, animals, monsters, etc. Most adult creatures die from impact but those who survive generally wait to heal some before hunting. Places that have had this weather for a long time are use to the event and may even desire it- the weather may be an important source of food for many. And, no, I do not suggest giant pizza slices and hot dogs. Other creatures may be considered speaking for the divine or are considered a plague.
Some clouds and rain are made up of energy. The most typical are obviously thunder and lightning. A lightning cloud may be bright enough to replace the sun and thunder clouds are invisible but impossible to ignore- they batter the land with sonic damage. Light clouds come in three forms- sun, moon and star. Each amplifies the light that strikes them, strengthening magic based on those kinds of light. http://skirmisher.com/node/687 has some ideas on forms of energy in d20 that can be used. Acid rain may be common and destructive in our world, but in a fantasy setting, it might be required for some kinds of plants and animals, ones that need it to power their exotic biologies.
Booze, medicines and such are possible. Nations war over areas that have rain that retards aging or keeps a plague at bay. Booze sounds like fun, but if there is enough of it, the locals have shortened lifespans (ruined livers does that). Monsters that can benefit from the weather will also try to control such areas. A flock of dragons will dominate control a mountain range where the rain provides resistance to the form of energy they are normally vulnerable to.
Magic, order, chaos, good and evil are weird things to consider for weather, but why not? While thinking about this, I came up with two ideas for magic. If all rain contains magic, then deserts will be low magic areas, they may even leech power right out of casters (take away the highest level of spells and then the next highest per week). Wastelands may have abundant life but their rain contains no magic and also has the leeching effect. The other four's effects are obvious.
And then there is combinations of the above. Rain may be highly acidic, causing caves to form by dissolving specific minerals. These minerals turn to gas and come back to the ground as soil that is immune to the acid. The result is layers of cave systems, much of which contain the remains of life that were covered by the soil.
There can be different layers of clouds, from fog banks to sunclouds, each with their own magical effects. Some have different effects when they mix.
Sorry about the delay in posting this- computer issues.
