In Dorastor, the Storm Spirit was captured by Lokamayadon and was bound in an experiment to try to gain influence over the Storm Dragon (in fact, he managed to merge the Storm Spirit with the Inhuman King of the Ralian Dragonewts, creating the Dragonewt of Storm, but this failed to influence the Storm Dragon). This meant that Dorastor was without a controlling Storm Spirit.
When Arkat came and ravaged Dorastor, many spirits and beings hid away and escaped his wrath. One of these was the Dragonewt of Storm. As it contained the Dorastoran Storm Spirit Dorastor had no proper weather of its own. The only rain which fell was blown in from outside, the only clouds were those which fleetingly passed by from elsewhere. This did not make for a pleasant place.
When Ralzakark was awakened by the God Learners he took many steps to improve the land of Dorastor which was then a blasted and sterile place. One of these steps was to replace the Storm Spirit of Dorastor. As Ralzakark had known Lokamayadon, he knew several Storm HeroQuests and began to search for a suitable Spirit. Eventually he made contact with the devastated Spirit of Ragnaglar, the Mad God and brought back his Breath to Dorastor. Ragnaglar's Breath was a fairly powerful Storm Spirit, being a grandson of Umath himself, and filled the vacuum perfectly.
However, because Ragnaglar was touched by madness and Chaos, his Breath did not act normally. From then on, the weather in Dorastor was unpredictable. Violent Storms would appear from nowhere and blast the land, sometimes a small cloud would settle over an individual and would gently rain on him wherever he went, the rainstorms in Dorastor were often made of things other than water, the wind was sometimes filled with stone, dust or metal, sometimes the rain would rip the souls from those it fell on.
In our campaign, while we were running on a round-robin basis, I often set scenarios in Dorastor and Ragnaglar's Breath was one of the things I used to set it as a dangerous place. For medium to high strength Rune Level parties, walking in Acid rain for more than a round is not pleasant as all their iron starts dissolving. For lower level parties these can be devastating. When I started GMing the campaign myself, I moved it to Dorastor and Ragnaglar's Breath became even more annoying as even Orlanthi could not predict what the Unusual Weather could be. Eventually the PCs located the Dragonewt of Storm and killed it in a certain manner, freeing the Storm Spirit and allowing the Inhuman King to be reborn as a True dragon. This had the effect of driving out Ragnaglar's Breath and making the weather more normal. However, the Breath was not completely replaced and still had a chance of appearing (1%) for old times sake.
In game terms, the weather in Dorastor was extreme, using a modified table from Griffin Mountain. In Summer it was hotter, in Winter colder. Storm Season had more violent Storms, Dark Season had more snow and more cold weather, Sea Season had harder rain and more flooding, Fire Season had incredibly hot days and occasional Electrical Storms which would appear from nowhere. Earth Season was always very mild due to the influence of Dorasta herself. However, each day there was a small chance (5-10% I think) of having unusual weather.
Unusual weather was rolled on a table (since in those days I liked random tables) and took various forms: